To find the area of the region defined by the set R={(x,y):xy≤8,1≤y≤x2}, we analyze the boundaries of the region in the first quadrant (where y≥1>0):
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Curves and Intersections:
- The lower boundary of the region is given by the line y=1.
- The upper boundary is bounded by the parabola y=x2 and the hyperbola y=x8.
- The intersection of y=x2 and y=1 occurs at x=1 (for x>0).
- The intersection of y=x2 and y=x8 gives x3=8⟹x=2.
- The intersection of y=x8 and y=1 occurs at x=8.
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Splitting the Region into Two Parts:
- For x∈[1,2]: The region is bounded above by y=x2 and below by y=1.
- For x∈[2,8]: The region is bounded above by y=x8 and below by y=1.
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Setting up the Definite Integrals:
Area A=∫12(x2−1)dx+∫28(x8−1)dx
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Evaluating the First Integral:
∫12(x2−1)dx=[3x3−x]12=(38−2)−(31−1)=32−(−32)=34
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Evaluating the Second Integral:
∫28(x8−1)dx=[8logex−x]28=(8loge8−8)−(8loge2−2)
=8(loge8−loge2)−6=8loge(28)−6=8loge4−6=16loge2−6
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Total Area:
A=34+16loge2−6=16loge2−314
Thus, the correct option is (A).