

Critical points occur where the gradient is zero. This is guaranteed whenever

and either

or

.
The Hessian matrix for this function looks like

and has determinant

Maxima occur whenever the determinant is positive and

. Minima occur whenever both the determinant and

are positive. Saddle points occur whenever the determinant is negative.
At

, you have a saddle point since the determinant reduces to -324, so

is the saddle point.
At

, the determinant is

and

, so

is a local maximum.
No other critical points remain, so you're done.
Answer:
13
Step-by-step explanation:
because I did the math and I learned this today it's simple
2n+9+5n=30 combine like terms on left side
7n+9=30 subtract 9 from both sides
7n=21 divide both sides by 7
n=3
Answer:
5x - 3
Step-by-step explanation:
Add like terms: (4x + x) + (-6 + 3) = 5x - 3