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>
If the scale factor of the small pool to the large pool is equal to 0.12, the ratio of their volumes should be equal to 0.12^3 or equal to 1.728 x 10^-3. We multiply this value to the given volume of the large pool to get the volume of the small pool.
volume of small pool = (1.728 x 10^-3)(15,000 m^3)
volume of small pool = 25.92 m^3
Hence, the answer is the first choice.
7) Vertex = V(2,3)
9) Vertex = V(2,1)
17) The smaller the absolute value of the coefficient of x², the larger is the opening of the parabola. (to compare, just take the absolute value of a)
Coefficients are (5), (-3) and (1):
Widest: f(x) =x², followed by f(x) = -3x² and the narrowest is f(x) =5x².
