Answer:48
Step-by-step explanation:
Total number of students=397
Students that travelled in a car=29
Let the students that travelled in a bus be represented by y.
Since 8 buses were filled, it will be 8y for total students
8y + 29= 397
8y= 397-29
8y= 368
Divide both side by 8
8y/8=368/8
y = 46
Number of students in each bus is 46
First, we need to get all of the r's on the same side. To do this, we need to subtract "r" from both sides.
0.25r - 0.125 + 0.5r - r = 0.5 + r - r
0.25r - 0.125 +0.5r - r = 0.5
Now, we need to add like terms.
0.25r + 0.5r - r - 0.125 = 0.5
-0.25r - 0.125 = 0.5
Now, we need to get the "r" variable by itself.
-0.25r - 0.125 + 0.125 = 0.5 + 0.125
-0.25r = 0.625
Now, we divide both sides by -0.25
(-0.25r) / (-0.25) = 0.625 / (-0.25)
r = -2.5
First, we have to convert our function (of x) into a function of y (we revolve the curve around the y-axis). So:

And the derivative of x:

Now, we can calculate the area of the surface:

We could calculate this integral (not very hard, but long), or use
(1),
(2) and
(3) to get:



Calculate indefinite integral:

And the area:
![A=2\pi\int\limits_0^{10}x\sqrt{4x^2+1}\,dx=2\pi\cdot\dfrac{1}{12}\bigg[\left(4x^2+1\right)^\frac{3}{2}\bigg]_0^{10}=\\\\\\= \dfrac{\pi}{6}\left[\big(4\cdot10^2+1\big)^\frac{3}{2}-\big(4\cdot0^2+1\big)^\frac{3}{2}\right]=\dfrac{\pi}{6}\Big(\big401^\frac{3}{2}-1^\frac{3}{2}\Big)=\boxed{\dfrac{401^\frac{3}{2}-1}{6}\pi}](https://tex.z-dn.net/?f=A%3D2%5Cpi%5Cint%5Climits_0%5E%7B10%7Dx%5Csqrt%7B4x%5E2%2B1%7D%5C%2Cdx%3D2%5Cpi%5Ccdot%5Cdfrac%7B1%7D%7B12%7D%5Cbigg%5B%5Cleft%284x%5E2%2B1%5Cright%29%5E%5Cfrac%7B3%7D%7B2%7D%5Cbigg%5D_0%5E%7B10%7D%3D%5C%5C%5C%5C%5C%5C%3D%20%5Cdfrac%7B%5Cpi%7D%7B6%7D%5Cleft%5B%5Cbig%284%5Ccdot10%5E2%2B1%5Cbig%29%5E%5Cfrac%7B3%7D%7B2%7D-%5Cbig%284%5Ccdot0%5E2%2B1%5Cbig%29%5E%5Cfrac%7B3%7D%7B2%7D%5Cright%5D%3D%5Cdfrac%7B%5Cpi%7D%7B6%7D%5CBig%28%5Cbig401%5E%5Cfrac%7B3%7D%7B2%7D-1%5E%5Cfrac%7B3%7D%7B2%7D%5CBig%29%3D%5Cboxed%7B%5Cdfrac%7B401%5E%5Cfrac%7B3%7D%7B2%7D-1%7D%7B6%7D%5Cpi%7D)
Answer D.
The equation show that it is a linear graph this means the graph is a straight line