SOLUTION: Given that f(x) = x^2 + ax + 15 has a minimum value of -12 what is a ?
think im missing something very simple in solving this problem.
its suppose to involve only algebra in
Question 400064: Given that f(x) = x^2 + ax + 15 has a minimum value of -12 what is a ?
think im missing something very simple in solving this problem.
its suppose to involve only algebra in order to solve but i got completely lost and tried using calculus which got me even more lost -- I was thinking minimum value -12 means lower limit of the parabula is -12 so i solved the derivative of the function to be that x =a/2 kept going for a while and got an answer that made no sense. soooo what am i missing how do i do this problem with just algebra? Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
Hi
f(x) = x^2 + ax + 15 with a minimum value of -12
f(x) = (x+ a/2)^2 - a^2/4 + 15
Using the vertex form of a parabola, where(h,k) is the vertex
-a^2/4 + 15 = -12
27 = a^2/4
27*4 = a^2
a = ± sqrt(108)