Question

Find the maximum or minimum of the following quadratic function: y = x2 - x - 56.

A. -56
B. 56
C. -225/4
D. 225/4

Answer 1

the x-value of the minimum is at -b/2a, so here 1/2. The y-value here is -225/4, or C

Answer 2

y=x^2-x+1/4-1/4-56
=(x-1/2)^2-(1+224)/4
=(x-1/2)^2-225/4
minimum value of y=-225/4 and is attained at x=1/2