Find the maximum and minimum value of the function y = x2 + 6x-7 in the interval [- 8,3]

Find the maximum and minimum value of the function y = x2 + 6x-7 in the interval [- 8,3]

solution
y=x²+6x-7
=(x²+6x+9)-9-7
=(x+3)²-16
The axis of symmetry is x = - 3 with the opening upward
x=-3∈[-8,3]
When x = - 3, the minimum value is: Ymin = - 16
When x = 3, the maximum value is obtained
ymax=20