Answer:
Step-by-step explanation:
1) 165
2) 108
3)24
4) 75
5)2
6)7
<h2>1st Equation:</h2>
Answer for A:

Answer for B:

<h2>2nd Equation:</h2>
Answer:

<u>hope it helps</u><u>.</u>

Divide both sides by
to get


Substitute
, so that
. Then



The remaining ODE is separable. Separating the variables gives

Integrate both sides. On the left, split up the integrand into partial fractions.




Then

On the right, we have

Solving for
explicitly is unlikely to succeed, so we leave the solution in implicit form,

and finally solve in terms of
by replacing
:



The formula of an area of a rectangle:
A = wl
We have l = w - 4 and A = 21.
Substitute:
w(w - 4) = 21 <em>use distributive property</em>
(w)(w) + (w)(-4) = 21
w² - 4w = 21 <em>subtract 21 from both sides</em>
w² - 4w - 21 = 0
w² - 7w + 3w - 21 = 0
w(w - 7) + 3(w - 7) = 0
(w - 7)(w + 3) = 0 ↔ w - 7 = 0 ∨ w + 3 = 0
w = 7 ∨ w = -3 < 0
l = w - 4 → l = 7 - 4 = 3
<h3>Answer: the length = 3 u.</h3>
-5
This is just to fill out the space of twenty characters