Answer:

Step-by-step explanation:
When you are given an expression in this format

You must find two numbers that add up to <em>b</em> while the product is <em>c</em>.
You do trial and error to figure it out for your equation.

Hmm... what two numbers add up to 1 and multiplied together equal -90.
Start off with pairs that can equal 90.
45 2
18 5
9 10
Ok, well 45 * 2 does equal 90 but 45 + 2 = 47and 45 + -2 = 43 but there's no way I can make it equal to 1. Next!
18 * 5 equals 90 but 18 + -5 = 13 and 18 + 5 = 23, I can just tell that there's no way I can make this equal to 1.
9 * 10 equals 90, 9 + 10 = 19 but 9 + -10 = -1. Now, that's interesting, We have -1 but we need 1. All we have to do is flip the order. 10 + -9 = 1. And -9 * 10 = -90, PERFECT!
Now use the two numbers and put it in factored form.
