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

1 Answer
Apr 6, 2018

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