1. By the chain rule,

I'm going to switch up the notation to save space, so for example,
is shorthand for
.

We have




Similarly,

where



To capture all the partial derivatives of
, compute its gradient:


2. The problem is asking for
and
. But
is already a function of
, so the chain rule isn't needed here. I suspect it's supposed to say "find
and
" instead.
If that's the case, then


as the hint suggests. We have



Putting everything together, we get


8(x - 6) = 4x
Distribute.
8x - 48 = 4x
Subtract 8x from both sides.
8x -8x - 48 =4x -8x
Now you have...
-48 = -4x
Divide -4 by both sides.
-48/-4 = -4x/-4
12 = x
The number is 12.
Answer:
20d + 30d
Step-by-step explanation:
20 and 30 minutes per day
Kelly can show 49 with 4 ten blocks and 9 one blocks, 49 ones blocks, and she take a one hundred grid block, places 4 tens on 4 columns of the 100 and 9 one blocks on one row of the 100 grid block.