The area of the region is:
- A
- B
- C
- D
The area of the region is:
Correct answer:D
Standard Method
Given: The region is .
Find: The area of the region.
The region is bounded by the curves , , and . The upper boundary changes where .
Find the point of intersection:
Set up the integrals:
For , the upper curve is . For , the upper curve is .
Evaluate the first integral:
Evaluate the second integral:
Add the results:
Therefore, the correct option is D.
Why the integral must be split
Given: The same region satisfies , , and .
Find: Why two separate integrals are required.
Since and in the region, this becomes . Together with , the actual upper boundary is the smaller of and .
The switch occurs when the two upper candidates are equal:
Also, from , we need , so . From , we need , so . Hence the interval is .
Thus the area is computed as
which evaluates to
So the correct option is D.
Using a single integral over the whole interval is incorrect because the upper boundary changes from to at . Always find the intersection point first and split the area accordingly.
Treating as only the curve is wrong. The inequality means the region lies below for , so it acts as a boundary condition on the admissible area.
Missing the -limits and leads to an incomplete region. These come from requiring the lower boundary to stay below the upper bounds, giving and .
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