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Matching quadratic equations with their correct solutions.

Table showing quadratic equations and their solutions for linking problems.

Table showing quadratic equations and their solutions for linking problems.

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Show Answer Key & Explanations Step-by-step solution for: Solving Quadratic Equations by Completing the Square - Link ...
Let's analyze the problem. You've provided a table with five quadratic equations (A to E) and their corresponding solutions. The task appears to be matching each quadratic equation to its correct solution — but in this case, some of the given solutions may be incorrect.

We'll go through each option one by one, solve the quadratic equation using the quadratic formula, and check whether the provided solution matches.

---

🔷 Quadratic Formula:


For $ ax^2 + bx + c = 0 $, the solutions are:

$$
x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
$$

---

Option A:


Equation: $ x^2 - 8x + 2 = 0 $
Given solution: $ x = 4 \pm \sqrt{19} $

Let’s compute:

- $ a = 1, b = -8, c = 2 $
- Discriminant: $ (-8)^2 - 4(1)(2) = 64 - 8 = 56 $
- So,
$$
x = \frac{8 \pm \sqrt{56}}{2} = \frac{8 \pm 2\sqrt{14}}{2} = 4 \pm \sqrt{14}
$$

But the given solution is $ 4 \pm \sqrt{19} $. Incorrect

---

Option B:


Equation: $ x^2 + 6x - 1 = 0 $
Given solution: $ x = 2 \pm \sqrt{3} $

Compute:

- $ a = 1, b = 6, c = -1 $
- Discriminant: $ 36 - 4(1)(-1) = 36 + 4 = 40 $
- $ x = \frac{-6 \pm \sqrt{40}}{2} = \frac{-6 \pm 2\sqrt{10}}{2} = -3 \pm \sqrt{10} $

Given: $ 2 \pm \sqrt{3} $ → Incorrect

---

Option C:


Equation: $ x^2 - 8x - 3 = 0 $
Given solution: $ x = 1 \pm \sqrt{6} $

Compute:

- $ a = 1, b = -8, c = -3 $
- Discriminant: $ 64 - 4(1)(-3) = 64 + 12 = 76 $
- $ x = \frac{8 \pm \sqrt{76}}{2} = \frac{8 \pm 2\sqrt{19}}{2} = 4 \pm \sqrt{19} $

Given: $ 1 \pm \sqrt{6} $ → Incorrect

---

Option D:


Equation: $ x^2 + 6x + 4 = 0 $
Given solution: $ x = \pm \sqrt{6} - 1 $

Compute:

- $ a = 1, b = 6, c = 4 $
- Discriminant: $ 36 - 16 = 20 $
- $ x = \frac{-6 \pm \sqrt{20}}{2} = \frac{-6 \pm 2\sqrt{5}}{2} = -3 \pm \sqrt{5} $

Given: $ \pm \sqrt{6} - 1 $ → That would be $ \sqrt{6} - 1 $ or $ -\sqrt{6} - 1 $

Compare: $ -3 \pm \sqrt{5} $ vs $ \pm \sqrt{6} - 1 $

Not the same → Incorrect

---

Option E:


Equation: $ x^2 - 4x + 1 = 0 $
Given solution: $ x = \pm 2\sqrt{5} - 4 $

Compute:

- $ a = 1, b = -4, c = 1 $
- Discriminant: $ 16 - 4 = 12 $
- $ x = \frac{4 \pm \sqrt{12}}{2} = \frac{4 \pm 2\sqrt{3}}{2} = 2 \pm \sqrt{3} $

Given: $ \pm 2\sqrt{5} - 4 $ → that’s $ 2\sqrt{5} - 4 $ or $ -2\sqrt{5} - 4 $

Clearly not equal to $ 2 \pm \sqrt{3} $ → Incorrect

---

🚨 Conclusion:



None of the given solutions match their respective equations.

But wait — perhaps the task is to find which pair (equation and solution) is correctly matched, i.e., identify which row has the correct solution?

Let’s recheck carefully.

Wait! Let's look again at Option D:
Equation: $ x^2 + 6x + 4 = 0 $
We found: $ x = -3 \pm \sqrt{5} $

But the given solution is: $ x = \pm \sqrt{6} - 1 $

That is: $ x = \sqrt{6} - 1 $ or $ x = -\sqrt{6} - 1 $

Let’s plug into original equation:

Try $ x = \sqrt{6} - 1 $:

$ (\sqrt{6} - 1)^2 + 6(\sqrt{6} - 1) + 4 = ? $

= $ (6 - 2\sqrt{6} + 1) + 6\sqrt{6} - 6 + 4 = (7 - 2\sqrt{6}) + 6\sqrt{6} - 6 + 4 $

= $ (7 - 6 + 4) + (-2\sqrt{6} + 6\sqrt{6}) = 5 + 4\sqrt{6} \ne 0 $

So not a solution.

Now let's try Option A again:

Equation: $ x^2 - 8x + 2 = 0 $

We found: $ x = 4 \pm \sqrt{14} $

But given: $ x = 4 \pm \sqrt{19} $

No.

Wait — maybe we made an error? Let’s double-check Option C:

C: $ x^2 - 8x - 3 = 0 $

Discriminant: $ 64 + 12 = 76 $

$ x = \frac{8 \pm \sqrt{76}}{2} = \frac{8 \pm 2\sqrt{19}}{2} = 4 \pm \sqrt{19} $

But given solution: $ x = 1 \pm \sqrt{6} $

Still wrong.

Wait — now consider Option B: $ x^2 + 6x - 1 = 0 $

We had: $ x = -3 \pm \sqrt{10} $

But given: $ x = 2 \pm \sqrt{3} $

Try plugging $ x = 2 + \sqrt{3} $ into $ x^2 + 6x - 1 $:

$ (2 + \sqrt{3})^2 + 6(2 + \sqrt{3}) - 1 = (4 + 4\sqrt{3} + 3) + 12 + 6\sqrt{3} - 1 = 7 + 4\sqrt{3} + 12 + 6\sqrt{3} - 1 = 18 + 10\sqrt{3} \ne 0 $

Nope.

Wait — what if the task is to find which equation has the solution matching the form?

Alternatively, maybe the table is meant to be matched, and we're supposed to correctly link them.

But all given solutions are wrong.

Wait — let's reverse it: Suppose the right-hand side (solution) is correct, and see which equation it solves.

Let’s test Option D's solution: $ x = \pm \sqrt{6} - 1 $

So possible roots: $ x = \sqrt{6} - 1 $ and $ x = -\sqrt{6} - 1 $

Sum: $ (\sqrt{6} - 1) + (-\sqrt{6} - 1) = -2 $

Product: $ (\sqrt{6} - 1)(-\sqrt{6} - 1) = -(\sqrt{6} - 1)(\sqrt{6} + 1) = -(6 - 1) = -5 $

So the quadratic would be: $ x^2 - (\text{sum})x + \text{product} = x^2 + 2x - 5 $

But Option D is $ x^2 + 6x + 4 $ → no.

Try Option A's solution: $ x = 4 \pm \sqrt{19} $

Then sum = 8, product = $ 16 - 19 = -3 $

So equation: $ x^2 - 8x - 3 = 0 $ → that's Option C

Ah! So solution $ x = 4 \pm \sqrt{19} $ belongs to equation C: $ x^2 - 8x - 3 = 0 $

But in the table, C has equation $ x^2 - 8x - 3 = 0 $, but solution $ x = 1 \pm \sqrt{6} $ → wrong.

But A has equation $ x^2 - 8x + 2 = 0 $, and solution $ x = 4 \pm \sqrt{19} $ → but that’s not correct, because discriminant is 56 → $ \sqrt{56} = 2\sqrt{14} $, so $ x = 4 \pm \sqrt{14} $

So none match.

But let’s try Option E: solution $ x = \pm 2\sqrt{5} - 4 $

That is: $ x = 2\sqrt{5} - 4 $ or $ x = -2\sqrt{5} - 4 $

Sum: $ (2\sqrt{5} - 4) + (-2\sqrt{5} - 4) = -8 $

Product: $ (2\sqrt{5} - 4)(-2\sqrt{5} - 4) = -[(2\sqrt{5})(2\sqrt{5}) + 4(2\sqrt{5}) - 4(2\sqrt{5}) - 16] $? Wait:

Better: use identity: $ (a)(b) $ where $ a = 2\sqrt{5} - 4 $, $ b = -2\sqrt{5} - 4 $

= $ (2\sqrt{5})(-2\sqrt{5}) + (2\sqrt{5})(-4) + (-4)(-2\sqrt{5}) + (-4)(-4) $

= $ -4*5 -8\sqrt{5} + 8\sqrt{5} + 16 = -20 + 16 = -4 $

So sum = -8, product = -4 → equation: $ x^2 + 8x - 4 = 0 $

But Option E is $ x^2 - 4x + 1 = 0 $ → no.

Wait — let's try Option B: $ x = 2 \pm \sqrt{3} $

Sum: $ 4 $, Product: $ (2)^2 - (\sqrt{3})^2 = 4 - 3 = 1 $

So equation: $ x^2 - 4x + 1 = 0 $ → that's Option E

So the solution $ x = 2 \pm \sqrt{3} $ corresponds to equation $ x^2 - 4x + 1 = 0 $

But in the table, E has equation $ x^2 - 4x + 1 = 0 $, but solution $ x = \pm 2\sqrt{5} - 4 $ → wrong.

But B has equation $ x^2 + 6x - 1 = 0 $, and solution $ x = 2 \pm \sqrt{3} $ → but that’s for $ x^2 - 4x + 1 = 0 $

So the correct pairing should be:

- Equation $ x^2 - 4x + 1 = 0 $ → solution $ x = 2 \pm \sqrt{3} $

But in the table, E has that equation, but wrong solution.

Similarly, B has $ x^2 + 6x - 1 = 0 $, which has solution $ x = -3 \pm \sqrt{10} $

Now, let’s try Option D: solution $ x = \pm \sqrt{6} - 1 $

As before: sum = -2, product = -5 → equation $ x^2 + 2x - 5 = 0 $

Not any of the listed.

Now try Option C: $ x^2 - 8x - 3 = 0 $

We computed: $ x = 4 \pm \sqrt{19} $

But given: $ x = 1 \pm \sqrt{6} $

Check: $ 1 + \sqrt{6} \approx 1 + 2.45 = 3.45 $, plug into $ x^2 - 8x - 3 $:

$ (3.45)^2 - 8*3.45 - 3 \approx 11.9 - 27.6 - 3 = -18.7 \ne 0 $

No.

Wait — what about Option A: $ x^2 - 8x + 2 = 0 $

Correct solution: $ x = 4 \pm \sqrt{14} $

But given: $ 4 \pm \sqrt{19} $ → close but not same.

But notice: only one of these equations has a solution that matches the form.

Wait — let’s try Option D: $ x^2 + 6x + 4 = 0 $

We have: $ x = -3 \pm \sqrt{5} $

Is there a way this could be written as $ \pm \sqrt{6} - 1 $? No.

But let’s try Option B: $ x^2 + 6x - 1 = 0 $

Solution: $ x = -3 \pm \sqrt{10} $

But given: $ 2 \pm \sqrt{3} $

No.

Wait — let’s try Option E: $ x^2 - 4x + 1 = 0 $

We know: $ x = 2 \pm \sqrt{3} $

But given: $ x = \pm 2\sqrt{5} - 4 $

Let’s compute $ 2\sqrt{5} \approx 4.47 $, so $ 4.47 - 4 = 0.47 $

Plug $ x = 0.47 $ into $ x^2 - 4x + 1 $: $ 0.22 - 1.88 + 1 = -0.66 \ne 0 $

No.

Wait — perhaps none are correct, but maybe the task is to identify which one is correct.

Let’s suppose the solution in Option C is wrong, but maybe another one is right.

Wait — let’s check Option D again.

Equation: $ x^2 + 6x + 4 = 0 $

Solve: $ x = \frac{-6 \pm \sqrt{36 - 16}}{2} = \frac{-6 \pm \sqrt{20}}{2} = \frac{-6 \pm 2\sqrt{5}}{2} = -3 \pm \sqrt{5} $

Given: $ x = \pm \sqrt{6} - 1 $

$ \sqrt{6} \approx 2.45 $, so $ \sqrt{6} - 1 \approx 1.45 $, $ -\sqrt{6} - 1 \approx -3.45 $

Plug $ x = -3.45 $ into $ x^2 + 6x + 4 $:

$ (11.9) + 6*(-3.45) + 4 = 11.9 - 20.7 + 4 = -4.8 \ne 0 $

No.

Now try Option A: $ x = 4 \pm \sqrt{19} $

$ \sqrt{19} \approx 4.36 $, so $ x \approx 8.36 $ or $ -0.36 $

Plug $ x = 8.36 $ into $ x^2 - 8x + 2 $:

$ 69.8 - 66.88 + 2 = 5.92 \ne 0 $

No.

Wait — what if the correct one is not listed?

But let’s try Option C's equation: $ x^2 - 8x - 3 = 0 $

We said: $ x = 4 \pm \sqrt{19} $

Let’s verify:

$ (4 + \sqrt{19})^2 - 8(4 + \sqrt{19}) - 3 = 16 + 8\sqrt{19} + 19 - 32 - 8\sqrt{19} - 3 = (35 - 35) + (8\sqrt{19} - 8\sqrt{19}) = 0 $

Yes! So $ x = 4 \pm \sqrt{19} $ is a solution to $ x^2 - 8x - 3 = 0 $

But in the table, C has equation $ x^2 - 8x - 3 = 0 $, but solution $ x = 1 \pm \sqrt{6} $ → wrong.

And A has equation $ x^2 - 8x + 2 = 0 $, but solution $ x = 4 \pm \sqrt{19} $ → which is for C, not A.

So the correct solution for C is $ x = 4 \pm \sqrt{19} $, but it's listed under A.

Similarly, A has equation $ x^2 - 8x + 2 = 0 $, which has solution $ x = 4 \pm \sqrt{14} $, but given $ 4 \pm \sqrt{19} $ → wrong.

So no row has both correct equation and correct solution.

But perhaps the task is to find which equation matches which solution, and the table is mislabeled.

Let’s list correct pairs:

1. $ x^2 - 8x + 2 = 0 $ → $ x = 4 \pm \sqrt{14} $
2. $ x^2 + 6x - 1 = 0 $ → $ x = -3 \pm \sqrt{10} $
3. $ x^2 - 8x - 3 = 0 $ → $ x = 4 \pm \sqrt{19} $
4. $ x^2 + 6x + 4 = 0 $ → $ x = -3 \pm \sqrt{5} $
5. $ x^2 - 4x + 1 = 0 $ → $ x = 2 \pm \sqrt{3} $

Now compare to given solutions:

- A: $ x = 4 \pm \sqrt{19} $ → matches C
- B: $ x = 2 \pm \sqrt{3} $ → matches E
- C: $ x = 1 \pm \sqrt{6} $ → doesn't match any
- D: $ x = \pm \sqrt{6} - 1 $ → not matching
- E: $ x = \pm 2\sqrt{5} - 4 $ → not matching

So only A's solution matches C's equation, and B's solution matches E's equation.

But in the table, they are paired incorrectly.

Therefore, the correct linkage is:

- A's solution ($ x = 4 \pm \sqrt{19} $) goes with C's equation
- B's solution ($ x = 2 \pm \sqrt{3} $) goes with E's equation

But since the table has them mismatched, none of the rows are correct.

However, if the task is to find which one has the correct solution, then none do.

But wait — let’s check if any of the given solutions are actually correct for their equations.

Let’s test Option D: $ x^2 + 6x + 4 = 0 $, given $ x = \pm \sqrt{6} - 1 $

Try $ x = \sqrt{6} - 1 \approx 2.45 - 1 = 1.45 $

$ (1.45)^2 + 6(1.45) + 4 = 2.1 + 8.7 + 4 = 14.8 \ne 0 $

No.

Try Option E: $ x = \pm 2\sqrt{5} - 4 $

$ 2\sqrt{5} \approx 4.47 $, so $ x = 0.47 $ or $ -8.47 $

Plug $ x = 0.47 $ into $ x^2 - 4x + 1 $: $ 0.22 - 1.88 + 1 = -0.66 \ne 0 $

No.

Try Option C: $ x = 1 \pm \sqrt{6} $

$ x = 1 + \sqrt{6} \approx 3.45 $

$ (3.45)^2 - 8*3.45 - 3 = 11.9 - 27.6 - 3 = -18.7 \ne 0 $

No.

Try Option B: $ x = 2 + \sqrt{3} \approx 3.73 $

$ (3.73)^2 + 6*3.73 - 1 = 13.9 + 22.38 - 1 = 35.28 \ne 0 $

No.

Try Option A: $ x = 4 + \sqrt{19} \approx 4 + 4.36 = 8.36 $

$ (8.36)^2 - 8*8.36 + 2 = 69.8 - 66.88 + 2 = 4.92 \ne 0 $

No.

So all given solutions are incorrect for their equations.

But wait — only one solution is mathematically valid for its equation?

Let’s try Option D: $ x = \pm \sqrt{6} - 1 $

We already did, not good.

Wait — let’s try Option C: $ x = 1 \pm \sqrt{6} $

$ x = 1 + \sqrt{6} $, plug into $ x^2 - 8x - 3 $:

$ (1 + \sqrt{6})^2 - 8(1 + \sqrt{6}) - 3 = 1 + 2\sqrt{6} + 6 - 8 - 8\sqrt{6} - 3 = (7 - 11) + (2\sqrt{6} - 8\sqrt{6}) = -4 - 6\sqrt{6} \ne 0 $

No.

So conclusion: none of the solutions are correct.

But perhaps the task is to identify the correct solution for each equation, or to find which one is correct.

Since none are correct, maybe there's a typo.

But let’s look at Option D: $ x^2 + 6x + 4 = 0 $, solution $ x = \pm \sqrt{6} - 1 $

Maybe it's meant to be $ x = -3 \pm \sqrt{5} $, but it's not.

Alternatively, maybe the solution $ x = \pm \sqrt{6} - 1 $ is for a different equation.

But based on calculation, no match is correct.

However, upon closer inspection, let's check Option B again.

Wait — Option B: $ x^2 + 6x - 1 = 0 $

Given solution: $ x = 2 \pm \sqrt{3} $

But $ x = 2 + \sqrt{3} \approx 3.73 $

$ (3.73)^2 + 6*3.73 - 1 = 13.9 + 22.38 - 1 = 35.28 \ne 0 $

No.

But what if the solution in Option B was meant to be for a different equation?

Perhaps the intended correct answer is none, but that seems unlikely.

Wait — let’s try Option E: $ x = \pm 2\sqrt{5} - 4 $

This is $ x = 2\sqrt{5} - 4 $ or $ x = -2\sqrt{5} - 4 $

Let’s compute $ x = -2\sqrt{5} - 4 \approx -4.47 - 4 = -8.47 $

Plug into $ x^2 - 4x + 1 $: $ 71.7 + 33.88 + 1 = 106.58 \ne 0 $

No.

After checking all, we conclude:

Only one of the solutions is correct for its equation — none are.

But wait — let’s try Option C with its solution: $ x = 1 \pm \sqrt{6} $

$ x = 1 + \sqrt{6} \approx 3.45 $

$ (3.45)^2 - 8*3.45 - 3 = 11.9 - 27.6 - 3 = -18.7 \ne 0 $

No.

But earlier we saw that the solution $ x = 4 \pm \sqrt{19} $ is correct for C's equation, but it's listed under A.

So the correct linkage is:

- A's equation ($ x^2 - 8x + 2 = 0 $) → $ x = 4 \pm \sqrt{14} $ (not given)
- B's equation ($ x^2 + 6x - 1 = 0 $) → $ x = -3 \pm \sqrt{10} $
- C's equation ($ x^2 - 8x - 3 = 0 $) → $ x = 4 \pm \sqrt{19} $
- D's equation ($ x^2 + 6x + 4 = 0 $) → $ x = -3 \pm \sqrt{5} $
- E's equation ($ x^2 - 4x + 1 = 0 $) → $ x = 2 \pm \sqrt{3} $

Now, comparing to given solutions:

- Only A's solution ($ x = 4 \pm \sqrt{19} $) matches C's equation
- Only B's solution ($ x = 2 \pm \sqrt{3} $) matches E's equation

So if the task is to find which solution is correct for its equation, then none are.

But if the task is to find which equation has the correct solution, then none do.

However, if the task is to match the correct solution to the correct equation, then:

- C's equation should have solution A's solution
- E's equation should have solution B's solution

But since the table pairs them differently, no row is correct.

Final Answer: None of the given solutions are correct for their corresponding equations.

But perhaps the intended answer is that Option C has the correct solution if we swap it.

Wait — let’s check if any solution is correct for any equation.

Try Option A's solution: $ x = 4 \pm \sqrt{19} $

Plug into C's equation: $ x^2 - 8x - 3 = 0 $

As before, it works.

So $ x = 4 \pm \sqrt{19} $ is correct for C, not A.

Similarly, $ x = 2 \pm \sqrt{3} $ is correct for E, not B.

So the only correct pairing is:

- C's equation with A's solution
- E's equation with B's solution

But in the table, they are swapped.

So the correct answer is that no row has the correct equation-solution pair.

But if you must choose one, perhaps the closest is C or A, but neither are correct.

Wait — let’s try Option D: $ x = \pm \sqrt{6} - 1 $

This is $ x = \sqrt{6} - 1 $ or $ x = -\sqrt{6} - 1 $

Sum: $ (\sqrt{6} - 1) + (-\sqrt{6} - 1) = -2 $

Product: $ (\sqrt{6} - 1)(-\sqrt{6} - 1) = - (6 - 1) = -5 $

So equation: $ x^2 + 2x - 5 = 0 $

Not in the list.

So after thorough analysis, we conclude:

> None of the given solutions are correct for their corresponding equations.

But if the task is to identify the correct solution for each equation, then the correct ones are:

- A: $ x = 4 \pm \sqrt{14} $
- B: $ x = -3 \pm \sqrt{10} $
- C: $ x = 4 \pm \sqrt{19} $
- D: $ x = -3 \pm \sqrt{5} $
- E: $ x = 2 \pm \sqrt{3} $

So the only one that appears in the table is C's solution, but it's not listed as such.

Therefore, the table contains no correct equation-solution pairs.

Final Answer: None of the given solutions are correct for their respective equations.
Parent Tip: Review the logic above to help your child master the concept of solving quadratic equations by completing the square worksheet.
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