A. What is asked?
1 answer:
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To be a function, it has to pass the vertical line test, which means a vertical line drawn anywhere in the graph should cut the graph only once, not more.
To be a one-to-one function, it has to pass the vertical line test as well as the horizontal line test, which means that a horizontal line drawn anywhere in the graph should cut the graph only once, not more.
<em>Of course, it passes the vertical line test, so its a function. </em>
<em>Does it pass the horizontal line test? </em><em>NO! </em><em>As shown in the attached picture, the blue line (horizontal line) cuts the graph at 3 places. We therefore eliminate choices A and B. We can eliminate choice C because nowhere is it required a function to pass through the origin for it to be one-to-one. Hence, the answer is D (blue line shows this).</em>
<em>ANSWER: D</em>
Answer:
The volume of the solid is
Step-by-step explanation:
In this case, the washer method seems to be easier and thus, it is the one I will use.
Since the rotation is around the y-axis we need to change de dependency of our variables to have . Thus, our functions with
as independent variable are:
For the washer method, we need to find the area function, which is given by:
By taking a look at the plot I attached, one can easily see that for a rotation around the y-axis the outer radius is given by the function and the inner one by
. Thus, the area function is:
Now we just need to integrate. The integration limits are easy to find by just solving the equation , which has two solutions
and
. These are then, our integration limits.
