So to solve this you need to reverse factor this problem
x^2 + 8x + 7 = 0
The common formula is this for factoring ax^2 + bx + c
Now you have to think what multplties to "c" and adds up to "b".
So in this case it's 7 x 1 = 7 and 7 + 1 = 8
So you set it up like this
(x + 7)(x + 1) = 0
So now you can check the factors by multiplying them together and see if it gets your original equation which is does.
So finally to get the answers you need to set each parenthesis to 0 and solve for x.
x + 7 = 0
x + 1 = 0
and we get x = -1 and - 7
You can also plug these two answers back into your original equation to see if it equals 0.
If you have any questions please feel free to comment