Let's solve each of these factoring problems step by step.
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1. Which of the following is a factor of $ x^2 - 10x + 24 $?
We need to factor $ x^2 - 10x + 24 $.
We look for two numbers that:
- Multiply to
24 (the constant term)
- Add to
-10 (the coefficient of the middle term)
Let’s list factor pairs of 24:
- $ 1 \times 24 $
- $ 2 \times 12 $
- $ 3 \times 8 $
- $ 4 \times 6 $
Now check which pair adds to -10:
- $ -4 + (-6) = -10 $, and $ (-4)(-6) = 24 $
So:
$$
x^2 - 10x + 24 = (x - 4)(x - 6)
$$
So the factors are $ x - 4 $ and $ x - 6 $.
Looking at the options:
A) $ x+6 $ → Not a factor
B) $ x-4 $ →
✔ Yes, this is a factor
C) $ x+4 $ → No
D) $ x-2 $ → No
✔ Answer: B) $ x - 4 $
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2. Factor: $ x^2 + 7x - 30 $
Find two numbers that:
- Multiply to
-30
- Add to
7
Try pairs:
- $ 10 \times (-3) = -30 $, $ 10 + (-3) = 7 $ →
✔
So:
$$
x^2 + 7x - 30 = (x + 10)(x - 3)
$$
Check:
$$
(x + 10)(x - 3) = x^2 - 3x + 10x - 30 = x^2 + 7x - 30
$$
✔ Answer: D) $ (x + 10)(x - 3) $
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3. Factor: $ x^2 + 9x - 36 $
Find two numbers that:
- Multiply to
-36
- Add to
9
Try:
- $ 12 \times (-3) = -36 $, $ 12 + (-3) = 9 $ →
✔
So:
$$
x^2 + 9x - 36 = (x + 12)(x - 3)
$$
Check:
$$
(x + 12)(x - 3) = x^2 - 3x + 12x - 36 = x^2 + 9x - 36
$$
✔ Answer: C) $ (x + 12)(x - 3) $
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4. Factor: $ a^2 - a - 12 $
Find two numbers that:
- Multiply to
-12
- Add to
-1
Try:
- $ -4 \times 3 = -12 $, $ -4 + 3 = -1 $ →
✔
So:
$$
a^2 - a - 12 = (a - 4)(a + 3)
$$
✔ Answer: A) $ (a - 4)(a + 3) $
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5. Which of the following is a factor of $ r^2 - 16r + 60 $?
Factor $ r^2 - 16r + 60 $
Find two numbers that:
- Multiply to
60
- Add to
-16
Try:
- $ -10 \times -6 = 60 $, $ -10 + (-6) = -16 $ →
✔
So:
$$
r^2 - 16r + 60 = (r - 10)(r - 6)
$$
Factors are $ r - 10 $ and $ r - 6 $
Check options:
A) $ r + 10 $ → No
B) $ r - 6 $ →
✔ Yes
C) $ r - 30 $ → No
D) $ r + 6 $ → No
✔ Answer: B) $ r - 6 $
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6. Factor: $ x^2 - 16x + 48 $
Find two numbers that:
- Multiply to
48
- Add to
-16
Try:
- $ -12 \times -4 = 48 $, $ -12 + (-4) = -16 $ →
✔
So:
$$
x^2 - 16x + 48 = (x - 12)(x - 4)
$$
Check:
$$
(x - 12)(x - 4) = x^2 - 4x - 12x + 48 = x^2 - 16x + 48
$$
✔ Answer: B) $ (x - 12)(x - 4) $
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✔ Final Answers:
1.
B – $ x - 4 $
2.
D – $ (x + 10)(x - 3) $
3.
C – $ (x + 12)(x - 3) $
4.
A – $ (a - 4)(a + 3) $
5.
B – $ r - 6 $
6.
B – $ (x - 12)(x - 4) $
Let me know if you'd like explanations for the rest!
Parent Tip: Review the logic above to help your child master the concept of math worksheet for 9th grade.