f(x)=x^2+ax+b
f ' (x) = 2x + a
but f ' (3) = 0
2(3) + a = 0
a = -6
so f(x) = x^2 - 6x + b
we also know that f(3) = 9
3^2 - 6(3) + b = 9
b = 18
Determine the values of a and b so that the function f(x)=x^2+ax+b has a minimum at (3, 9).
1 answer