Answer:
x=5,-7
Explanation:
First, we must look at what factors multiply to -35 but ad up to +2. For this problem that would be -5 and +7.
Now we are going to replace the +2x with the factors we found (which are -5x and +7x). Now our equation looks like this:
f(x)= x^2 -5x+7x-35
Next, lets group these four terms into two groups:
(x^2-5x) (7x-35)
What can we divide out of the groups?
We can take an x out of the first: x(x-5)
And we can take a 7 out of the second: 7(x-5)
Now we will keep the (x-5) and group what we took out (x+7)
Finally solve for x for both (x-5) and (x+7)
x-5=0 x+7=0
x=5 x=-7