SOLUTION: Let f(x)=3x^2-8x. find a such that f(a)=-5.

Question 240777: Let f(x)=3x^2-8x. find a such that f(a)=-5.
Answer by jsmallt9(3758) (Show Source): You can put this solution on YOUR website!
If , then . And if f(a) = -5 then .

Now we just solve for a. Since this is a quadratic equation we will
1) Get one side equal to zero (by adding 5 to each side):

2) Factor (and use the Zero Product Property) or use the Quadratic Formula.

By the Zero Product Property, this or any product can be zero only if one (or more) of the factors is zero. So
or
Solving these two equations we get:
or
of (You will get these same answers if you use the Quadratic formula correctly.)
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