We can factor out 4 so:
4y²+4y-8 = 4(y²+y-2)
Now we need to factor out y²+y-2
Method 1:
We check the factors of 2 which should have a difference of 1, and they do. They are 1 and 2. So: y²+y-2 = (y+2)(y-1)
Method 2: Quadratic Formula
x = -1 ± √(1²+8) = -1 ± √9 = -1 ± 3 = -2 or 1
2 2 2
So: y²+y-2 = (y+2)(y-1)
Therefore, 4y²+4y-8=4(y+2)(y-1)