# How do you find the critical points and local max and min for #y=4x-x^2#?

##### 1 Answer

Nov 23, 2016

Maximum at

#### Explanation:

Although we can use calculus sometimes an intuitive common sense approach is quicker and easier.

If

The function has a -ve coefficient of

graph{4x-x^2 [-10, 10, -5, 5]}

**Using Calculus**

At critical point,

To establish min or max we look at the 2nd derivative:

When