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

do you know the greatest common factor of 10,2,8?

Answer 2

2

Answer 3

great
so when you factor out 2 you have
\[10x^2+2x-8 \\ 2(5)x^2+2(1)x-2(4) \\ 2(5x^2+1x-4)\]
now let's look at factoring the thingy in ( )
That is let's look at factoring:
\[5x^2+1x-4 \text{ aka } 5x^2+x-4\]

Answer 4

notice
a=5
b=1
c=-4
you are looking for two factors of ac that have product ac and sum b

Answer 5

that is what two integer numbers when you multiply them give you -20
and when you add them give you 1

Answer 6

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

Answer 7

so b

Answer 8

Remember to not give direct answers in the future. Thank you kindly.

Answer 9

ok sorry