How do you solve #x^2 + 3x - 40 = 0#?

1 Answer
Apr 4, 2016

The answers for #x^2+3x−40=0# are -8 and 5.


For this problem, we are able to factor. Since 8 and 5 are both factors of 40, and since 8-5=3, we will use 8 and 5 in our binomial equation: #(x+8)(x-5)=40#. Just to prove that this is correct, let's multiply the two together: #x^2-5x+8x-40=x^2+3x-40#. From here, we can use the zero product property to get our answers: #x+8=0, x-5=0#. Subtract 8 from the first equation and subtract 5 from the second equation to get our answers, -8 and 5.