Question

How do you factor `2x ^ { 2} + 21x = - 40`?

Answer 1

the answer is `x=-8 & x=-5/2`

Explanation:

first add `40` to both sides to make it equal to `0` and now you get `2x^2+21x+40=0` now find two numbers that multiply to give you `80(2*40)` and add to give you `21` you get `16,5` and now you put it in `2x^2+16x+5x+40=0` now group then and take out what you can and you'll get `2x(x+8)+5(x+8)` the two parenthesis have to be the same. now you have `(2x+5)(x+8)` but since it's equal to `0`, you have to solve. so now you set them both to `0` and you just solve for `x` and you get your answer