(a) See the attached sketch. Each shell will have a radius <em>y</em> chosen from the interval [2, 4], a height of <em>x</em> = 2/<em>y</em>, and thickness ∆<em>y</em>. For infinitely many shells, we have ∆<em>y</em> converging to 0, and each super-thin shell contributes an infinitesimal volume of
2<em>π</em> (radius)² (height) = 4<em>πy</em>
Then the volume of the solid is obtained by integrating over [2, 4]:

(b) See the other attached sketch. (The text is a bit cluttered, but hopefully you'll understand what is drawn.) Each shell has a radius 9 - <em>x</em> (this is the distance between a given <em>x</em> value in the orange shaded region to the axis of revolution) and a height of 8 - <em>x</em> ³ (and this is the distance between the line <em>y</em> = 8 and the curve <em>y</em> = <em>x</em> ³). Then each shell has a volume of
2<em>π</em> (9 - <em>x</em>)² (8 - <em>x</em> ³) = 2<em>π</em> (648 - 144<em>x</em> + 8<em>x</em> ² - 81<em>x</em> ³ + 18<em>x</em> ⁴ - <em>x</em> ⁵)
so that the overall volume of the solid would be

I leave the details of integrating to you.
Answer:
In 5 years, the price increased about 30%.
I am not good at perentages, so correct me if I'm wrong. Also this is an estimation, not the exact percentage.
Answer:
B. 45
Step-by-step explanation:
do 12×12 which is 144 then Davide it by 2 because it's a triangle then do 9×3 which is 27 then subtract that from 72 and you get 45.
Answer:
The two graphs are perpendicular
Step-by-step explanation:
The slope of the first one is the reciprocal of the second. Also I graphed it.
Answer:
False
Step-by-step explanation:
Angles a and b add to 180° (linear pair), so angle b is 68°.