An ellipse (by Kepler in 16th century)
Nora's speed (5*8)m²/2h= 20 m²/h.
Zack's speed (4*9)m²/3h= 12 m²/h
Together for 1 h they paint (20+12) m²/h=32m²/h
Given area (10*12)m²=120 m²
120m² *1h/32m² = 3.75 h (3h 45 min) to paint 10m*12m together.
Cross sections of the volume are washers or annuli with outer radii <em>x(y)</em> + 1, where
<em>y</em> = <em>x(y) </em>² - 1 ==> <em>x(y)</em> = √(<em>y</em> + 1)
and inner radii 1. The distance between the outermost edge of each shell to the axis of revolution is then 1 + √(<em>y</em> + 1), and the distance between the innermost edge of <em>R</em> on the <em>y</em>-axis to the axis of revolution is 1.
For each value of <em>y</em> in the interval [-1, 3], the corresponding cross section has an area of
<em>π</em> (1 + √(<em>y</em> + 1))² - <em>π</em> (1)² = <em>π</em> (2√(<em>y</em> + 1) + <em>y</em> + 1)
Then the volume of the solid is the integral of this area over [-1, 3]:
Answer:
4th one
Step-by-step explanation:
if you add them
Answer:
y = -6, x =2
Step-by-step explanation:
To solve by elimination, you have to line both equations up together. Then, you multiply both equations until one variable is removed.
2x+y = -2
5x + 3y = - 8
There are many different ways to solve an elimination problem, but generally you should look for the simplest route. Here, I would multiply the top equation by -3.
-6x -3y = 6
5x +3y = -8
Imagine you are adding the two equations together. You end up with
-x = -2
Then solve for x. In this situation, it is fairly simple. Take out a factor of -1.
x = 2
Finally, choose one of your beginning equations and plug your new-found x value back into the equation.
2(2) +y = -2
4 + y = -2
y = -6
