The Lagrangian for this function and the given constraints is

which has partial derivatives (set equal to 0) satisfying

This is a fairly standard linear system. Solving yields Lagrange multipliers of

and

, and at the same time we find only one critical point at

.
Check the Hessian for

, given by


is positive definite, since

for any vector

, which means

attains a minimum value of

at

. There is no maximum over the given constraints.
Answer:
The third one
Step-by-step explanation:
Answer:
It will be £2520
Step-by-step explanation:
- 3.2=


- 320


Answer:
10 times as much
Step-by-step explanation:
the 2 in 82 is worth 2 ones while the 2 in 21 is worth 10 ones