Solve radical equations to find the value of the unknown variable.
Worksheet titled "Radical Equations" with ten problems requiring solving for unknown variables, featuring square roots and algebraic expressions.
JPG
742×1050
79.5 KB
Free · Personal Use
Quality Assured by Worksheets Library Team
Reviewed for educational accuracy and age-appropriateness
ID: #927557
⭐
Show Answer Key & Explanations
Step-by-step solution for: Solving Radical Equations Worksheets - Math Monks
▼
Show Answer Key & Explanations
Step-by-step solution for: Solving Radical Equations Worksheets - Math Monks
Let's solve each of the radical equations step by step. Radical equations involve variables under a radical (square root, cube root, etc.). The key strategy is to isolate the radical, then square (or cube, etc.) both sides to eliminate it, and finally check for extraneous solutions.
---
Step 1: Square both sides:
$$
(\sqrt{p + 9})^2 = 1^2 \Rightarrow p + 9 = 1
$$
Step 2: Solve for $p$:
$$
p = 1 - 9 = -8
$$
Check:
$$
\sqrt{-8 + 9} = \sqrt{1} = 1 \quad \text{✓ Valid}
$$
✔ Answer: $p = -8$
---
Step 1: Divide both sides by 10:
$$
\sqrt{9g} = 6
$$
Step 2: Square both sides:
$$
9g = 36
$$
Step 3: Solve for $g$:
$$
g = \frac{36}{9} = 4
$$
Check:
$$
10\sqrt{9 \cdot 4} = 10\sqrt{36} = 10 \cdot 6 = 60 \quad \text{✓ Valid}
$$
✔ Answer: $g = 4$
---
Let’s isolate one radical:
$$
\sqrt{x + 11} = 11 - \sqrt{x}
$$
Step 1: Square both sides:
$$
(\sqrt{x + 11})^2 = (11 - \sqrt{x})^2
\Rightarrow x + 11 = 121 - 22\sqrt{x} + x
$$
Step 2: Simplify:
$$
x + 11 = 121 + x - 22\sqrt{x}
$$
Subtract $x$ from both sides:
$$
11 = 121 - 22\sqrt{x}
$$
Step 3: Solve:
$$
-110 = -22\sqrt{x} \Rightarrow \sqrt{x} = 5
$$
Step 4: Square both sides:
$$
x = 25
$$
Check:
$$
\sqrt{25} + \sqrt{25 + 11} = 5 + \sqrt{36} = 5 + 6 = 11 \quad \text{✓ Valid}
$$
✔ Answer: $x = 25$
---
This is a fourth root, so raise both sides to the 4th power:
$$
(\sqrt[4]{2p + 2})^4 = 3^4 \Rightarrow 2p + 2 = 81
$$
Step 2: Solve:
$$
2p = 79 \Rightarrow p = \frac{79}{2} = 39.5
$$
Check:
$$
\sqrt[4]{2(39.5) + 2} = \sqrt[4]{79 + 2} = \sqrt[4]{81} = 3 \quad \text{✓ Valid}
$$
✔ Answer: $p = \frac{79}{2}$ or $39.5$
---
Step 1: Isolate the radical:
$$
\sqrt{2 - x} = x + 7 - 3 = x + 4
$$
Step 2: Square both sides:
$$
(\sqrt{2 - x})^2 = (x + 4)^2 \Rightarrow 2 - x = x^2 + 8x + 16
$$
Step 3: Bring all terms to one side:
$$
0 = x^2 + 8x + 16 + x - 2 = x^2 + 9x + 14
$$
Factor:
$$
x^2 + 9x + 14 = (x + 7)(x + 2) = 0
\Rightarrow x = -7 \text{ or } x = -2
$$
Check both:
- $x = -7$:
$\sqrt{2 - (-7)} + 3 = \sqrt{9} + 3 = 3 + 3 = 6$
Right side: $-7 + 7 = 0$ → $6 \ne 0$ ✘ Invalid
- $x = -2$:
$\sqrt{2 - (-2)} + 3 = \sqrt{4} + 3 = 2 + 3 = 5$
Right side: $-2 + 7 = 5$ → ✓ Valid
✔ Answer: $x = -2$
---
Step 1: Square both sides:
$$
(\sqrt{2b + 3})^2 = (\sqrt{5b - 3})^2 \Rightarrow 2b + 3 = 5b - 3
$$
Step 2: Solve:
$$
3 + 3 = 5b - 2b \Rightarrow 6 = 3b \Rightarrow b = 2
$$
Check:
$$
\sqrt{2(2) + 3} = \sqrt{7}, \quad \sqrt{5(2) - 3} = \sqrt{7} \quad \text{✓ Valid}
$$
✔ Answer: $b = 2$
---
Step 1: Square both sides:
$$
(2f)^2 = (\sqrt{4f^2 + 6f - 12})^2 \Rightarrow 4f^2 = 4f^2 + 6f - 12
$$
Step 2: Subtract $4f^2$ from both sides:
$$
0 = 6f - 12 \Rightarrow 6f = 12 \Rightarrow f = 2
$$
Check:
Left: $2(2) = 4$
Right: $\sqrt{4(4) + 6(2) - 12} = \sqrt{16 + 12 - 12} = \sqrt{16} = 4$ → ✓ Valid
✔ Answer: $f = 2$
---
Step 1: Square both sides:
$$
(\sqrt{2t + 15})^2 = t^2 \Rightarrow 2t + 15 = t^2
$$
Step 2: Rearrange:
$$
t^2 - 2t - 15 = 0
$$
Factor:
$$
(t - 5)(t + 3) = 0 \Rightarrow t = 5 \text{ or } t = -3
$$
Check:
- $t = 5$: $\sqrt{2(5) + 15} = \sqrt{10 + 15} = \sqrt{25} = 5$ → ✓ Valid
- $t = -3$: $\sqrt{2(-3) + 15} = \sqrt{-6 + 15} = \sqrt{9} = 3$, but right side is $-3$ → $3 \ne -3$ ✘ Invalid
✔ Answer: $t = 5$
---
This one is more complex. Let’s try to simplify and check possible values.
Let’s assume $x$ is such that all radicals are defined:
- $x + 1 \geq 0 \Rightarrow x \geq -1$
- $2x \geq 0 \Rightarrow x \geq 0$
- $x - 4 \geq 0 \Rightarrow x \geq 4$
So domain: $x \geq 4$
Try $x = 4$:
- LHS: $2\sqrt{5} - \sqrt{8} \approx 2(2.236) - 2.828 = 4.472 - 2.828 = 1.644$
- RHS: $\sqrt{0} = 0$ → Not equal
Try $x = 5$:
- LHS: $2\sqrt{6} - \sqrt{10} \approx 2(2.45) - 3.16 = 4.9 - 3.16 = 1.74$
- RHS: $\sqrt{1} = 1$ → No
Try $x = 9$:
- LHS: $2\sqrt{10} - \sqrt{18} \approx 2(3.16) - 4.24 = 6.32 - 4.24 = 2.08$
- RHS: $\sqrt{5} \approx 2.236$ → Close but not equal
Try $x = 16$:
- LHS: $2\sqrt{17} - \sqrt{32} \approx 2(4.123) - 5.657 = 8.246 - 5.657 = 2.589$
- RHS: $\sqrt{12} \approx 3.464$ → No
Try $x = 25$:
- LHS: $2\sqrt{26} - \sqrt{50} \approx 2(5.1) - 7.07 = 10.2 - 7.07 = 3.13$
- RHS: $\sqrt{21} \approx 4.58$ → No
Wait — maybe try squaring both sides carefully.
Let:
$$
2\sqrt{x+1} - \sqrt{2x} = \sqrt{x - 4}
$$
Isolate one radical. Move $\sqrt{2x}$ to the right:
$$
2\sqrt{x+1} = \sqrt{x - 4} + \sqrt{2x}
$$
Now square both sides:
$$
(2\sqrt{x+1})^2 = (\sqrt{x - 4} + \sqrt{2x})^2
\Rightarrow 4(x+1) = (x - 4) + 2\sqrt{(x - 4)(2x)} + 2x
$$
Simplify:
$$
4x + 4 = x - 4 + 2x + 2\sqrt{2x(x - 4)}
\Rightarrow 4x + 4 = 3x - 4 + 2\sqrt{2x(x - 4)}
$$
Subtract $3x - 4$:
$$
x + 8 = 2\sqrt{2x(x - 4)}
$$
Divide both sides by 2:
$$
\frac{x + 8}{2} = \sqrt{2x(x - 4)}
$$
Now square again:
$$
\left(\frac{x + 8}{2}\right)^2 = 2x(x - 4)
\Rightarrow \frac{(x + 8)^2}{4} = 2x^2 - 8x
$$
Multiply both sides by 4:
$$
(x + 8)^2 = 8x^2 - 32x
\Rightarrow x^2 + 16x + 64 = 8x^2 - 32x
$$
Bring all terms to one side:
$$
0 = 7x^2 - 48x - 64
$$
Use quadratic formula:
$$
x = \frac{48 \pm \sqrt{(-48)^2 - 4(7)(-64)}}{2(7)} = \frac{48 \pm \sqrt{2304 + 1792}}{14} = \frac{48 \pm \sqrt{4096}}{14}
$$
$\sqrt{4096} = 64$
$$
x = \frac{48 \pm 64}{14}
\Rightarrow x = \frac{112}{14} = 8 \quad \text{or} \quad x = \frac{-16}{14} = -\frac{8}{7}
$$
But $x \geq 4$, so only $x = 8$ is in domain.
Check $x = 8$:
LHS: $2\sqrt{9} - \sqrt{16} = 2(3) - 4 = 6 - 4 = 2$
RHS: $\sqrt{8 - 4} = \sqrt{4} = 2$ → ✓ Valid
✔ Answer: $x = 8$
---
Step 1: Isolate radical:
$$
\sqrt{10m - 1} = 13 - 10 = 3
$$
Step 2: Square both sides:
$$
10m - 1 = 9 \Rightarrow 10m = 10 \Rightarrow m = 1
$$
Check:
$$
10 + \sqrt{10(1) - 1} = 10 + \sqrt{9} = 10 + 3 = 13 \quad \text{✓ Valid}
$$
✔ Answer: $m = 1$
---
| Problem | Answer |
|--------|--------|
| 1 | $p = -8$ |
| 2 | $g = 4$ |
| 3 | $x = 25$ |
| 4 | $p = \frac{79}{2}$ |
| 5 | $x = -2$ |
| 6 | $b = 2$ |
| 7 | $f = 2$ |
| 8 | $t = 5$ |
| 9 | $x = 8$ |
| 10 | $m = 1$ |
Let me know if you'd like these formatted as a printable answer sheet!
---
1. $\sqrt{p + 9} = 1$
Step 1: Square both sides:
$$
(\sqrt{p + 9})^2 = 1^2 \Rightarrow p + 9 = 1
$$
Step 2: Solve for $p$:
$$
p = 1 - 9 = -8
$$
Check:
$$
\sqrt{-8 + 9} = \sqrt{1} = 1 \quad \text{✓ Valid}
$$
✔ Answer: $p = -8$
---
2. $10\sqrt{9g} = 60$
Step 1: Divide both sides by 10:
$$
\sqrt{9g} = 6
$$
Step 2: Square both sides:
$$
9g = 36
$$
Step 3: Solve for $g$:
$$
g = \frac{36}{9} = 4
$$
Check:
$$
10\sqrt{9 \cdot 4} = 10\sqrt{36} = 10 \cdot 6 = 60 \quad \text{✓ Valid}
$$
✔ Answer: $g = 4$
---
3. $\sqrt{x} + \sqrt{x + 11} = 11$
Let’s isolate one radical:
$$
\sqrt{x + 11} = 11 - \sqrt{x}
$$
Step 1: Square both sides:
$$
(\sqrt{x + 11})^2 = (11 - \sqrt{x})^2
\Rightarrow x + 11 = 121 - 22\sqrt{x} + x
$$
Step 2: Simplify:
$$
x + 11 = 121 + x - 22\sqrt{x}
$$
Subtract $x$ from both sides:
$$
11 = 121 - 22\sqrt{x}
$$
Step 3: Solve:
$$
-110 = -22\sqrt{x} \Rightarrow \sqrt{x} = 5
$$
Step 4: Square both sides:
$$
x = 25
$$
Check:
$$
\sqrt{25} + \sqrt{25 + 11} = 5 + \sqrt{36} = 5 + 6 = 11 \quad \text{✓ Valid}
$$
✔ Answer: $x = 25$
---
4. $\sqrt[4]{2p + 2} = 3$
This is a fourth root, so raise both sides to the 4th power:
$$
(\sqrt[4]{2p + 2})^4 = 3^4 \Rightarrow 2p + 2 = 81
$$
Step 2: Solve:
$$
2p = 79 \Rightarrow p = \frac{79}{2} = 39.5
$$
Check:
$$
\sqrt[4]{2(39.5) + 2} = \sqrt[4]{79 + 2} = \sqrt[4]{81} = 3 \quad \text{✓ Valid}
$$
✔ Answer: $p = \frac{79}{2}$ or $39.5$
---
5. $\sqrt{2 - x} + 3 = x + 7$
Step 1: Isolate the radical:
$$
\sqrt{2 - x} = x + 7 - 3 = x + 4
$$
Step 2: Square both sides:
$$
(\sqrt{2 - x})^2 = (x + 4)^2 \Rightarrow 2 - x = x^2 + 8x + 16
$$
Step 3: Bring all terms to one side:
$$
0 = x^2 + 8x + 16 + x - 2 = x^2 + 9x + 14
$$
Factor:
$$
x^2 + 9x + 14 = (x + 7)(x + 2) = 0
\Rightarrow x = -7 \text{ or } x = -2
$$
Check both:
- $x = -7$:
$\sqrt{2 - (-7)} + 3 = \sqrt{9} + 3 = 3 + 3 = 6$
Right side: $-7 + 7 = 0$ → $6 \ne 0$ ✘ Invalid
- $x = -2$:
$\sqrt{2 - (-2)} + 3 = \sqrt{4} + 3 = 2 + 3 = 5$
Right side: $-2 + 7 = 5$ → ✓ Valid
✔ Answer: $x = -2$
---
6. $\sqrt{2b + 3} = \sqrt{5b - 3}$
Step 1: Square both sides:
$$
(\sqrt{2b + 3})^2 = (\sqrt{5b - 3})^2 \Rightarrow 2b + 3 = 5b - 3
$$
Step 2: Solve:
$$
3 + 3 = 5b - 2b \Rightarrow 6 = 3b \Rightarrow b = 2
$$
Check:
$$
\sqrt{2(2) + 3} = \sqrt{7}, \quad \sqrt{5(2) - 3} = \sqrt{7} \quad \text{✓ Valid}
$$
✔ Answer: $b = 2$
---
7. $2f = \sqrt{4f^2 + 6f - 12}$
Step 1: Square both sides:
$$
(2f)^2 = (\sqrt{4f^2 + 6f - 12})^2 \Rightarrow 4f^2 = 4f^2 + 6f - 12
$$
Step 2: Subtract $4f^2$ from both sides:
$$
0 = 6f - 12 \Rightarrow 6f = 12 \Rightarrow f = 2
$$
Check:
Left: $2(2) = 4$
Right: $\sqrt{4(4) + 6(2) - 12} = \sqrt{16 + 12 - 12} = \sqrt{16} = 4$ → ✓ Valid
✔ Answer: $f = 2$
---
8. $\sqrt{2t + 15} = t$
Step 1: Square both sides:
$$
(\sqrt{2t + 15})^2 = t^2 \Rightarrow 2t + 15 = t^2
$$
Step 2: Rearrange:
$$
t^2 - 2t - 15 = 0
$$
Factor:
$$
(t - 5)(t + 3) = 0 \Rightarrow t = 5 \text{ or } t = -3
$$
Check:
- $t = 5$: $\sqrt{2(5) + 15} = \sqrt{10 + 15} = \sqrt{25} = 5$ → ✓ Valid
- $t = -3$: $\sqrt{2(-3) + 15} = \sqrt{-6 + 15} = \sqrt{9} = 3$, but right side is $-3$ → $3 \ne -3$ ✘ Invalid
✔ Answer: $t = 5$
---
9. $2\sqrt{x + 1} - \sqrt{2x} = \sqrt{x - 4}$
This one is more complex. Let’s try to simplify and check possible values.
Let’s assume $x$ is such that all radicals are defined:
- $x + 1 \geq 0 \Rightarrow x \geq -1$
- $2x \geq 0 \Rightarrow x \geq 0$
- $x - 4 \geq 0 \Rightarrow x \geq 4$
So domain: $x \geq 4$
Try $x = 4$:
- LHS: $2\sqrt{5} - \sqrt{8} \approx 2(2.236) - 2.828 = 4.472 - 2.828 = 1.644$
- RHS: $\sqrt{0} = 0$ → Not equal
Try $x = 5$:
- LHS: $2\sqrt{6} - \sqrt{10} \approx 2(2.45) - 3.16 = 4.9 - 3.16 = 1.74$
- RHS: $\sqrt{1} = 1$ → No
Try $x = 9$:
- LHS: $2\sqrt{10} - \sqrt{18} \approx 2(3.16) - 4.24 = 6.32 - 4.24 = 2.08$
- RHS: $\sqrt{5} \approx 2.236$ → Close but not equal
Try $x = 16$:
- LHS: $2\sqrt{17} - \sqrt{32} \approx 2(4.123) - 5.657 = 8.246 - 5.657 = 2.589$
- RHS: $\sqrt{12} \approx 3.464$ → No
Try $x = 25$:
- LHS: $2\sqrt{26} - \sqrt{50} \approx 2(5.1) - 7.07 = 10.2 - 7.07 = 3.13$
- RHS: $\sqrt{21} \approx 4.58$ → No
Wait — maybe try squaring both sides carefully.
Let:
$$
2\sqrt{x+1} - \sqrt{2x} = \sqrt{x - 4}
$$
Isolate one radical. Move $\sqrt{2x}$ to the right:
$$
2\sqrt{x+1} = \sqrt{x - 4} + \sqrt{2x}
$$
Now square both sides:
$$
(2\sqrt{x+1})^2 = (\sqrt{x - 4} + \sqrt{2x})^2
\Rightarrow 4(x+1) = (x - 4) + 2\sqrt{(x - 4)(2x)} + 2x
$$
Simplify:
$$
4x + 4 = x - 4 + 2x + 2\sqrt{2x(x - 4)}
\Rightarrow 4x + 4 = 3x - 4 + 2\sqrt{2x(x - 4)}
$$
Subtract $3x - 4$:
$$
x + 8 = 2\sqrt{2x(x - 4)}
$$
Divide both sides by 2:
$$
\frac{x + 8}{2} = \sqrt{2x(x - 4)}
$$
Now square again:
$$
\left(\frac{x + 8}{2}\right)^2 = 2x(x - 4)
\Rightarrow \frac{(x + 8)^2}{4} = 2x^2 - 8x
$$
Multiply both sides by 4:
$$
(x + 8)^2 = 8x^2 - 32x
\Rightarrow x^2 + 16x + 64 = 8x^2 - 32x
$$
Bring all terms to one side:
$$
0 = 7x^2 - 48x - 64
$$
Use quadratic formula:
$$
x = \frac{48 \pm \sqrt{(-48)^2 - 4(7)(-64)}}{2(7)} = \frac{48 \pm \sqrt{2304 + 1792}}{14} = \frac{48 \pm \sqrt{4096}}{14}
$$
$\sqrt{4096} = 64$
$$
x = \frac{48 \pm 64}{14}
\Rightarrow x = \frac{112}{14} = 8 \quad \text{or} \quad x = \frac{-16}{14} = -\frac{8}{7}
$$
But $x \geq 4$, so only $x = 8$ is in domain.
Check $x = 8$:
LHS: $2\sqrt{9} - \sqrt{16} = 2(3) - 4 = 6 - 4 = 2$
RHS: $\sqrt{8 - 4} = \sqrt{4} = 2$ → ✓ Valid
✔ Answer: $x = 8$
---
10. $10 + \sqrt{10m - 1} = 13$
Step 1: Isolate radical:
$$
\sqrt{10m - 1} = 13 - 10 = 3
$$
Step 2: Square both sides:
$$
10m - 1 = 9 \Rightarrow 10m = 10 \Rightarrow m = 1
$$
Check:
$$
10 + \sqrt{10(1) - 1} = 10 + \sqrt{9} = 10 + 3 = 13 \quad \text{✓ Valid}
$$
✔ Answer: $m = 1$
---
✔ Final Answers:
| Problem | Answer |
|--------|--------|
| 1 | $p = -8$ |
| 2 | $g = 4$ |
| 3 | $x = 25$ |
| 4 | $p = \frac{79}{2}$ |
| 5 | $x = -2$ |
| 6 | $b = 2$ |
| 7 | $f = 2$ |
| 8 | $t = 5$ |
| 9 | $x = 8$ |
| 10 | $m = 1$ |
Let me know if you'd like these formatted as a printable answer sheet!
Parent Tip: Review the logic above to help your child master the concept of radical equations worksheet with answers.