Question

Factor completely: 10x2 + 2x - 8

2(5x - 1)(x + 4)

2(5x - 4)(x + 1)

2(5x + 2)(x - 2)

2(5x - 2)(x + 2)

Answer 1

FAN AND MEDAL

Answer 2

2 (x+1) (5 x-4)

Answer 3

10x2 + 2x - 8

1. Factor out the common term 2
2(5x2+x−4)

2. Factor 5x2+x−4:
1. Multiply 5 by -4, which is -20.
2. Answer: 5 and -4
3. Rewrite 1x as the sum of 5x and −4x:
2(5x2+5x−4x−4)

3. Factor out common terms in the first two terms, then in the last two terms
2(5x(x+1)−4(x+1))

4. Factor out the common term x+1
2(x+1)(5x−4) <--- answer

Answer 4

Thank you~!!

Answer 5

Hello,

So, since we are given the answers, we can use trial and error. Lets try A.

* 2(5x - 1)(x + 4)
- Foil
2(5x^2 + 20x - x - 4)

Then we multiply by 2

10x^2 + 22x - 2x - 4
Add like terms: 10x^2 - 20x - 4

This clearly isn't it. We would do this for all the other answers given.

So lets try B:

2(5x - 4)(x + 1)
Foil:2( 5x^2 + 5x - 4x - 4)

Multiply: 10x^2 + 10x - 8x - 8

Now, if we subtract 10x from 8x, we're left with...?