If there is such a scalar function <em>f</em>, then



Integrate both sides of the first equation with respect to <em>x</em> :

Differentiate both sides with respect to <em>y</em> :


Integrate both sides with respect to <em>y</em> :

Plug this into the equation above with <em>f</em> , then differentiate both sides with respect to <em>z</em> :



Integrate both sides with respect to <em>z</em> :

So we end up with

Answer:
$260
Step-by-step explanation:
you multiply $65 by 4 for the set of four and the product is $260.
3.50x + 5 < 30
Ellie wants to spend less than 30, so it’ll be less than.
Answer:
By using cross multiplication
Step-by-step explanation:
ANSWER:
b) No
c) Yes
EXPLANATION:

b)
3 (-8 + 1) = 3 x -8 + 3
(3 x -8) (3 x +1) = 3 x -8 + 3 (just put left and right sides into calcu separately)
-72 = -21
Both sides are not equal and therefore it isn't a solution.
c)
3 (0.5 + 1) = 3 x 0.5 + 3
(3 x 0.5) (3 x +1) = 3 x 0.5 + 3
4.5 = 4.5
Both sides are equal and thereofre it IS a solution.