jonas practice guitar for 2 hours in 2 years. Bradley practice 4 more hours the joans. How many more practice id Bradley did the
1 answer:
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I gather you're supposed to compute the integral of over a surface
that is the part of the parabolic cylinder
with
and
.
We can parameterize by
with the given constraints on and
. Take the normal vector to
to be
so that the surface element is
Then in the integral, we have
Answer: Choice D
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Explanation:
The left portion is the interval (-∞, -2)
This is a shorthand way of saying
The curved parenthesis says "do not include this endpoint as part of the solution set". Note the open hole at x = -2 in the diagram.
In contrast, the value x = 4 is included (due to the filled in circle), so we use a square bracket for this endpoint. Therefore, the right-hand portion is represented by [4, ∞) which translates to
Negative and positive infinity will always use a parenthesis, and never a square bracket. This is because we can only approach infinity but never reach it, so we cannot include it as an endpoint.
All of this builds up to the full interval notation to be
The only square bracket is near the 4; everything else is a curved parenthesis. This is why choice D is the final answer.