So firstly, what two terms have a product of 8x^2 and a sum of 9x? That would be x and 8x. Replace 9x with x + 8x:
Next, factor x^2 + x and 8x + 8 separately. Make sure that they have the same quantity on the inside:
Now you can rewrite the equation as
Now using zero product property, solve for x:
<u>In short, the solutions are {-1,-8}, or C.</u>