Answer: Choice C
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Explanation:
The graph is shown below. The base of the 3D solid is the blue region. It spans from x = 0 to x = 1. It's also above the x axis, and below the curve 
Think of the blue region as the floor of this weirdly shaped 3D room.
We're told that the cross sections are perpendicular to the x axis and each cross section is a square. The side length of each square is 
where 0 < x < 1
Let's compute the area of each general cross section.
We'll be integrating infinitely many of these infinitely thin square slabs to find the volume of the 3D shape. Think of it like stacking concrete blocks together, except the blocks are side by side (instead of on top of each other). Or you can think of it like a row of square books of varying sizes. The books are very very thin.
This is what we want to compute
Apply a u-substitution
u = -2x
du/dx = -2
du = -2dx
dx = du/(-2)
dx = -0.5du
Also, don't forget to change the limits of integration
- If x = 0, then u = -2x = -2(0) = 0
- If x = 1, then u = -2x = -2(1) = -2
This means,
I used the rule that 
which says swapping the limits of integration will have us swap the sign out front.
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Furthermore,
![\displaystyle 0.5\int_{-2}^{0}e^{u}du = \frac{1}{2}\left[e^u+C\right]_{-2}^{0}\\\\\\= \frac{1}{2}\left[(e^0+C)-(e^{-2}+C)\right]\\\\\\= \frac{1}{2}\left[1 - \frac{1}{e^2}\right]](https://tex.z-dn.net/?f=%5Cdisplaystyle%200.5%5Cint_%7B-2%7D%5E%7B0%7De%5E%7Bu%7Ddu%20%3D%20%5Cfrac%7B1%7D%7B2%7D%5Cleft%5Be%5Eu%2BC%5Cright%5D_%7B-2%7D%5E%7B0%7D%5C%5C%5C%5C%5C%5C%3D%20%5Cfrac%7B1%7D%7B2%7D%5Cleft%5B%28e%5E0%2BC%29-%28e%5E%7B-2%7D%2BC%29%5Cright%5D%5C%5C%5C%5C%5C%5C%3D%20%5Cfrac%7B1%7D%7B2%7D%5Cleft%5B1%20-%20%5Cfrac%7B1%7D%7Be%5E2%7D%5Cright%5D)
In short,
![\displaystyle \int_{0}^{1}e^{-2x}dx = \frac{1}{2}\left[1 - \frac{1}{e^2}\right]](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cint_%7B0%7D%5E%7B1%7De%5E%7B-2x%7Ddx%20%3D%20%5Cfrac%7B1%7D%7B2%7D%5Cleft%5B1%20-%20%5Cfrac%7B1%7D%7Be%5E2%7D%5Cright%5D)
This points us to choice C as the final answer.
There are 22 books total on the shelf and 9 of them are biographical books so the probability is 9/22
The total cost for one can is: $25.41.
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Let us assume that we want to know the total cost of ONE CAN.
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To calculate our answer:
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$ 23.97 + [ (6/100) * 23.97)] = Our answer, in dollars.
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Note: "6%" = 6/100 = 0.06
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Rewrite as:
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$ 23.97 + [ (6/100) * 23.97)] = our answer, in dollars;
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$ 23.97 + (0.06 * 23.97)
= $ 23.97 + 1.4382
= $ 25.4082 ; Round to decimal places, to get:
<span>→ $ 25.41
</span>__________________________________________
Answer:
There needs to be 300 liters of Drink A and 270 liters of Drink B
Step-by-step explanation:
Let a = the amount of Drink A and b = the amount of Drink B
Multiplying a number by 0.2 is the same as calculating 20% of it and same goes with 15% and 0.15. This makes our equation for the amount of fruit juice:
0.2a + 0.15b = 100.5
We know what the difference between a and b will be 30 liters so:
a - b = 30
Now we have our system of equations
To cancel out a, we can multiply the first equation by -5 so we will now have:
-a - 0.75b = -502.5
a - b = 30
Adding these two equations together, we get:
-1.75b = -472.5
Both sides are negative, so we can take the negative signs away.
1.75b = 472.5
Now divide both sides by 1.75
b = 270
Plugging 270 into b, we have:
a - b = 30
a - 270 = 30
Add 270 to both sides
a = 300
There needs to be 300 liters of Drink A and 270 liters of Drink B
