Find the values of b such that the function has the given maximum value.
f(x)=-x^2 +bx-15 Maximum value: 66
the vertex is at x = b/2, so you want
-(b^2/4)+b(b/2)-15 = 66
b^2/4 = 81
b = ±18
f(x)=-x^2 +bx-15 Maximum value: 66
-(b^2/4)+b(b/2)-15 = 66
b^2/4 = 81
b = ±18