Question

Differentiating :

Differentiate A=l*w with respect to w

Answer 1

how does it end up as
\[A=w*l\]
\[\frac{ dA }{ dw }=w*\frac{ dl }{ dw }+l\]

Where did that +l come from?

Answer 2

by the product rule

Answer 3

dA/dw = w* dL /dw + d(w)/dw * L
dA/dw = w* dL /dw + 1 * L

Answer 4

l is a function of w

Answer 5

thanks!

Answer 6

you have to assume l is a function of w for that to make sense.
otherwise you would end with
dA/dw = L * 1, since L is a constant with respect to w

Answer 7

yes

Answer 8

can you please also explain what happens here
\[4r^2=l^2+w^2\]

the model answers show that 4r^2 differentiates to zero

Answer 9

again i am differentiating with respect to w

Answer 10

@jayzdd