can you help me with these questions?

merve

New member
Joined
Nov 2, 2010
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10
1) Sketch the region enclosed by \(\displaystyle 2y = 4 \sqrt{x}, \;\ y=5\), and \(\displaystyle 2y + 3 x = 7\)
Decide whether to integrate with respect to x or y, and then find the area of the region.
The area is?

2) Consider the area between the graphs \(\displaystyle x+ 2 y = 18\) and \(\displaystyle x + 6 = y^{2}\). This area can be computed in two different ways using integrals


\(\displaystyle \int_{a}^{b} f(x)dx + \int_{b}^{c} g(x)dx\)

Alternatively this area can be computed as a single integral
\(\displaystyle \int_{\alpha}^{\beta} h(y)dy\)

where \(\displaystyle \alpha\) = ? \(\displaystyle \beta =\)?
h(y) =?

3) Find the volume of the solid formed by rotating the region enclosed by
\(\displaystyle x=0, \quad x=1, \quad y=0, \quad y= 5 +x^{8}\)
about the x-axis.
Volume?

4)The volume of the solid obtained by rotating the region enclosed by
\(\displaystyle y = \frac{1}{x^{3}}, \quad y = 0, \quad x = 2, \quad \mbox{ and } x = 7\),
about the line y=-3 can be computed using the method of disks or washers via an integral
\(\displaystyle \displaystyle V = \int_{a}^{b}\) ?
with limits of integration a = ? and b = .?
The volume is V =? cubic units

5) Find the volume of the solid obtained by rotating the region bounded by the given curves about the specified axis.
\(\displaystyle x+y=4, \quad x = 5-(y-1)^{2}\) ;
about the x-axis.
Volume = ?

6) A car drives down a road in such a way that its velocity ( in m/s) at time t (seconds) is
\(\displaystyle v(t) = t^{1/2} + 4\)
.
Find the car's average velocity (in m/s) between t = 3 and t = 8.

7) One fine day in New York the low temperature occurs at 5 a.m.
and the high temperature at 5 p.m. The temperature varies
sinusoidally all day.
The temperature t hours after midnight is
\(\displaystyle T(t) = A + B \sin \left( \frac{\pi (t-C)}{12} \right)\)

where A, B, and C are certain constants.
The low temperature is 40 and the high temperature is 60 (Fahrenheit).
Find the average temperature during the first 6 hours after noon.
Hint: The high and low temperatures can be used together to find
A and B. Determine C from the fact that it is hottest at 5 p.m.
 
4)The volume of the solid obtained by rotating the region enclosed by
\(\displaystyle y = \frac{1}{x^{3}}, \quad y = 0, \quad x = 2, \quad \mbox{ and } x = 7\),
about the line y=-3 can be computed using the method of disks or washers via an integral
\(\displaystyle \displaystyle V = \int_{a}^{b}\) ?
with limits of integration a = ? and b = .?
The volume is V =? cubic units

Washers:

\(\displaystyle {\pi}\int_{2}^{7}\left[\left(\frac{1}{x^{3}}+3\right)^{2}-(-3)^{2}\right]dx\)

The graph appears below so you can get an idea what it looks like.


7) One fine day in New York the low temperature occurs at 5 a.m and the high temperature at 5 p.m. The temperature varies
sinusoidally all day.
The temperature t hours after midnight is
\(\displaystyle T(t) = A + B \sin \left( \frac{\pi (t-C)}{12} \right)\)

where A, B, and C are certain constants.
The low temperature is 40 and the high temperature is 60 (Fahrenheit).
Find the average temperature during the first 6 hours after noon.
Hint: The high and low temperatures can be used together to find
A and B. Determine C from the fact that it is hottest at 5 p.m.


\(\displaystyle \text{B=high-average}\)

The average temperature is \(\displaystyle A=\frac{\text{high+low}}{2}\)

\(\displaystyle C=\text{hours after midnight that the average occurs}\)

In other words, since 5 am is the low and 5 pm is the high, what time of day is in between?.

How many hours is this after midnight?. This gives C.

From this info you should be able to find A, B, and C.
 
merve said:
I have solved 4th one but not 7th one :(

merve, you have the nerve to post a list of several problems. And you *claim*
to have done #4, but you supplied zero amount of work for it and any other
problems. You are not being helped.

And no users here should give you answers (it's not help) when you
don't do your part first.
 
Let's start with #4. What did you get?.

How about #7?. What did you get for A, B, and C?.

Let's tackle these, then we can proceed with the other problems.
 
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