Question

the maximum value of 5+20x-4x²​

Answer 1

To find stationary points, differentiate and set the differential to zero.

In this case, y=5+20x−4x2. When we differentiating, terms without an x ‘disappear’ and terms with an xn ‘change’ to nxn−1

Therefore, dydx=20−8x.

Setting this equal to zero, 20−8x=0

8x=20

x=208=52.