Polynomial division practice worksheet with eight problems, designed for educational use.
Worksheet titled "Computation with Polynomials: Division" featuring eight polynomial division problems, with the EdBoost logo and website URL at the bottom.
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Show Answer Key & Explanations
Step-by-step solution for: Computation with Polynomials: Division | EdBoost.
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Show Answer Key & Explanations
Step-by-step solution for: Computation with Polynomials: Division | EdBoost.
Let's solve each polynomial division problem step by step using long division or synthetic division where appropriate. We'll go through each one carefully.
---
We use polynomial long division:
```
x - 5
_________
x - 8 | x² -13x +40
-(x² - 8x)
-----------
-5x +40
-(-5x +40)
-----------
0
```
✔ Quotient: $ x - 5 $, Remainder: 0
So: $ \frac{x^2 - 13x + 40}{x - 8} = x - 5 $
---
Long division:
```
3x - 6
_________
4x - 5 | 12x² -39x +30
-(12x² -15x)
-------------
-24x +30
-(-24x +30)
-------------
0
```
✔ Quotient: $ 3x - 6 $, Remainder: 0
So: $ \frac{12x^2 - 39x + 30}{4x - 5} = 3x - 6 $
---
```
2x + 9
_________
7x + 3 | 14x² +69x +27
-(14x² +6x)
------------
63x +27
-(63x +27)
------------
0
```
✔ Quotient: $ 2x + 9 $, Remainder: 0
So: $ \frac{14x^2 + 69x + 27}{7x + 3} = 2x + 9 $
---
Use long division:
```
2x² + 7x + 1
_______________
3x + 1 | 6x³ +23x² +10x +1
-(6x³ + 2x²)
--------------
21x² +10x
-(21x² +7x)
------------
3x +1
-(3x +1)
-------
0
```
✔ Quotient: $ 2x^2 + 7x + 1 $, Remainder: 0
So: $ \frac{6x^3 + 23x^2 + 10x + 1}{3x + 1} = 2x^2 + 7x + 1 $
---
Long division:
```
3x + 1
_________
x - 2 | 3x² -5x -22
-(3x² -6x)
-----------
x -22
-(x -2)
--------
-20
```
✔ Quotient: $ 3x + 1 $, Remainder: $ -20 $
So: $ \frac{3x^2 - 5x - 22}{x - 2} = 3x + 1 - \frac{20}{x - 2} $
---
```
7x + 46
_________
x - 3 | 7x² +25x +12
-(7x² -21x)
------------
46x +12
-(46x -138)
------------
150
```
Wait! Let’s double-check that subtraction:
After $ 46x + 12 $, subtract $ (46x - 138) $ → $ 46x + 12 - 46x + 138 = 150 $
✔ Quotient: $ 7x + 46 $, Remainder: $ 150 $
So: $ \frac{7x^2 + 25x + 12}{x - 3} = 7x + 46 + \frac{150}{x - 3} $
But wait — let's verify if this is correct by plugging in $ x = 3 $ into the original expression:
Numerator at $ x = 3 $: $ 7(9) + 25(3) + 12 = 63 + 75 + 12 = 150 $
Denominator: $ 3 - 3 = 0 $ → undefined, but remainder should be $ f(3) = 150 $, which matches.
So yes, correct.
✔ Final: $ 7x + 46 + \frac{150}{x - 3} $
---
Note: $ x^2 - 9 = (x - 3)(x + 3) $
We divide a cubic by a quadratic.
Use long division:
```
5x + 4
_________
x² - 9 | 5x³ +4x² -45x -36
-(5x³ -45x)
------------
4x² +0x -36
-(4x² -36)
------------
0
```
Wait — let’s do it properly:
Divide $ 5x^3 $ by $ x^2 $ → $ 5x $
Multiply: $ 5x(x^2 - 9) = 5x^3 - 45x $
Subtract:
$$
(5x^3 + 4x^2 - 45x - 36) - (5x^3 - 45x) = 4x^2 + 0x - 36
$$
Now divide $ 4x^2 $ by $ x^2 $ → $ 4 $
Multiply: $ 4(x^2 - 9) = 4x^2 - 36 $
Subtract:
$$
(4x^2 + 0x - 36) - (4x^2 - 36) = 0
$$
✔ Quotient: $ 5x + 4 $, Remainder: 0
So: $ \frac{5x^3 + 4x^2 - 45x - 36}{x^2 - 9} = 5x + 4 $
---
This is more complex. Use long division.
We divide a degree-5 polynomial by a degree-2 polynomial.
Step-by-step:
#### Step 1: $ \frac{5x^5}{5x^2} = x^3 $
Multiply: $ x^3(5x^2 + 2) = 5x^5 + 2x^3 $
Subtract:
$$
(5x^5 - 45x^4 + 52x^3 - 18x^2 + 20) - (5x^5 + 2x^3) = -45x^4 + 50x^3 - 18x^2 + 20
$$
#### Step 2: $ \frac{-45x^4}{5x^2} = -9x^2 $
Multiply: $ -9x^2(5x^2 + 2) = -45x^4 - 18x^2 $
Subtract:
$$
(-45x^4 + 50x^3 - 18x^2 + 20) - (-45x^4 - 18x^2) = 50x^3 + 0x^2 + 20
$$
#### Step 3: $ \frac{50x^3}{5x^2} = 10x $
Multiply: $ 10x(5x^2 + 2) = 50x^3 + 20x $
Subtract:
$$
(50x^3 + 0x^2 + 20) - (50x^3 + 20x) = 0x^3 + 0x^2 - 20x + 20
$$
#### Step 4: $ \frac{-20x}{5x^2} = -\frac{4}{x} $ → not valid for polynomial division.
So we stop here.
Current quotient: $ x^3 - 9x^2 + 10x $
Remainder: $ -20x + 20 $
So:
$$
\frac{5x^5 - 45x^4 + 52x^3 - 18x^2 + 20}{5x^2 + 2} = x^3 - 9x^2 + 10x + \frac{-20x + 20}{5x^2 + 2}
$$
We can factor numerator of remainder: $ -20x + 20 = -20(x - 1) $
So final answer:
✔ $ x^3 - 9x^2 + 10x - \frac{20(x - 1)}{5x^2 + 2} $
---
1) $ x - 5 $
2) $ 3x - 6 $
3) $ 2x + 9 $
4) $ 2x^2 + 7x + 1 $
5) $ 3x + 1 - \frac{20}{x - 2} $
6) $ 7x + 46 + \frac{150}{x - 3} $
7) $ 5x + 4 $
8) $ x^3 - 9x^2 + 10x - \frac{20(x - 1)}{5x^2 + 2} $
Let me know if you'd like these checked with synthetic division (where applicable) or graphed!
---
1) Divide: $ \frac{x^2 - 13x + 40}{x - 8} $
We use polynomial long division:
```
x - 5
_________
x - 8 | x² -13x +40
-(x² - 8x)
-----------
-5x +40
-(-5x +40)
-----------
0
```
✔ Quotient: $ x - 5 $, Remainder: 0
So: $ \frac{x^2 - 13x + 40}{x - 8} = x - 5 $
---
2) Divide: $ \frac{12x^2 - 39x + 30}{4x - 5} $
Long division:
```
3x - 6
_________
4x - 5 | 12x² -39x +30
-(12x² -15x)
-------------
-24x +30
-(-24x +30)
-------------
0
```
✔ Quotient: $ 3x - 6 $, Remainder: 0
So: $ \frac{12x^2 - 39x + 30}{4x - 5} = 3x - 6 $
---
3) Divide: $ \frac{14x^2 + 69x + 27}{7x + 3} $
```
2x + 9
_________
7x + 3 | 14x² +69x +27
-(14x² +6x)
------------
63x +27
-(63x +27)
------------
0
```
✔ Quotient: $ 2x + 9 $, Remainder: 0
So: $ \frac{14x^2 + 69x + 27}{7x + 3} = 2x + 9 $
---
4) Divide: $ \frac{6x^3 + 23x^2 + 10x + 1}{3x + 1} $
Use long division:
```
2x² + 7x + 1
_______________
3x + 1 | 6x³ +23x² +10x +1
-(6x³ + 2x²)
--------------
21x² +10x
-(21x² +7x)
------------
3x +1
-(3x +1)
-------
0
```
✔ Quotient: $ 2x^2 + 7x + 1 $, Remainder: 0
So: $ \frac{6x^3 + 23x^2 + 10x + 1}{3x + 1} = 2x^2 + 7x + 1 $
---
5) Divide: $ \frac{3x^2 - 5x - 22}{x - 2} $
Long division:
```
3x + 1
_________
x - 2 | 3x² -5x -22
-(3x² -6x)
-----------
x -22
-(x -2)
--------
-20
```
✔ Quotient: $ 3x + 1 $, Remainder: $ -20 $
So: $ \frac{3x^2 - 5x - 22}{x - 2} = 3x + 1 - \frac{20}{x - 2} $
---
6) Divide: $ \frac{7x^2 + 25x + 12}{x - 3} $
```
7x + 46
_________
x - 3 | 7x² +25x +12
-(7x² -21x)
------------
46x +12
-(46x -138)
------------
150
```
Wait! Let’s double-check that subtraction:
After $ 46x + 12 $, subtract $ (46x - 138) $ → $ 46x + 12 - 46x + 138 = 150 $
✔ Quotient: $ 7x + 46 $, Remainder: $ 150 $
So: $ \frac{7x^2 + 25x + 12}{x - 3} = 7x + 46 + \frac{150}{x - 3} $
But wait — let's verify if this is correct by plugging in $ x = 3 $ into the original expression:
Numerator at $ x = 3 $: $ 7(9) + 25(3) + 12 = 63 + 75 + 12 = 150 $
Denominator: $ 3 - 3 = 0 $ → undefined, but remainder should be $ f(3) = 150 $, which matches.
So yes, correct.
✔ Final: $ 7x + 46 + \frac{150}{x - 3} $
---
7) Divide: $ \frac{5x^3 + 4x^2 - 45x - 36}{x^2 - 9} $
Note: $ x^2 - 9 = (x - 3)(x + 3) $
We divide a cubic by a quadratic.
Use long division:
```
5x + 4
_________
x² - 9 | 5x³ +4x² -45x -36
-(5x³ -45x)
------------
4x² +0x -36
-(4x² -36)
------------
0
```
Wait — let’s do it properly:
Divide $ 5x^3 $ by $ x^2 $ → $ 5x $
Multiply: $ 5x(x^2 - 9) = 5x^3 - 45x $
Subtract:
$$
(5x^3 + 4x^2 - 45x - 36) - (5x^3 - 45x) = 4x^2 + 0x - 36
$$
Now divide $ 4x^2 $ by $ x^2 $ → $ 4 $
Multiply: $ 4(x^2 - 9) = 4x^2 - 36 $
Subtract:
$$
(4x^2 + 0x - 36) - (4x^2 - 36) = 0
$$
✔ Quotient: $ 5x + 4 $, Remainder: 0
So: $ \frac{5x^3 + 4x^2 - 45x - 36}{x^2 - 9} = 5x + 4 $
---
8) Divide: $ \frac{5x^5 - 45x^4 + 52x^3 - 18x^2 + 20}{5x^2 + 2} $
This is more complex. Use long division.
We divide a degree-5 polynomial by a degree-2 polynomial.
Step-by-step:
#### Step 1: $ \frac{5x^5}{5x^2} = x^3 $
Multiply: $ x^3(5x^2 + 2) = 5x^5 + 2x^3 $
Subtract:
$$
(5x^5 - 45x^4 + 52x^3 - 18x^2 + 20) - (5x^5 + 2x^3) = -45x^4 + 50x^3 - 18x^2 + 20
$$
#### Step 2: $ \frac{-45x^4}{5x^2} = -9x^2 $
Multiply: $ -9x^2(5x^2 + 2) = -45x^4 - 18x^2 $
Subtract:
$$
(-45x^4 + 50x^3 - 18x^2 + 20) - (-45x^4 - 18x^2) = 50x^3 + 0x^2 + 20
$$
#### Step 3: $ \frac{50x^3}{5x^2} = 10x $
Multiply: $ 10x(5x^2 + 2) = 50x^3 + 20x $
Subtract:
$$
(50x^3 + 0x^2 + 20) - (50x^3 + 20x) = 0x^3 + 0x^2 - 20x + 20
$$
#### Step 4: $ \frac{-20x}{5x^2} = -\frac{4}{x} $ → not valid for polynomial division.
So we stop here.
Current quotient: $ x^3 - 9x^2 + 10x $
Remainder: $ -20x + 20 $
So:
$$
\frac{5x^5 - 45x^4 + 52x^3 - 18x^2 + 20}{5x^2 + 2} = x^3 - 9x^2 + 10x + \frac{-20x + 20}{5x^2 + 2}
$$
We can factor numerator of remainder: $ -20x + 20 = -20(x - 1) $
So final answer:
✔ $ x^3 - 9x^2 + 10x - \frac{20(x - 1)}{5x^2 + 2} $
---
✔ Final Answers Summary:
1) $ x - 5 $
2) $ 3x - 6 $
3) $ 2x + 9 $
4) $ 2x^2 + 7x + 1 $
5) $ 3x + 1 - \frac{20}{x - 2} $
6) $ 7x + 46 + \frac{150}{x - 3} $
7) $ 5x + 4 $
8) $ x^3 - 9x^2 + 10x - \frac{20(x - 1)}{5x^2 + 2} $
Let me know if you'd like these checked with synthetic division (where applicable) or graphed!
Parent Tip: Review the logic above to help your child master the concept of algebraic long division worksheet pdf.