Let W 1
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be the solid half-cone bounded by z= x 2
+y 2
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,z=4 and the yz-plane with x≥0, and let Let W 2
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be the solid half-cone bounded by z= x 2
+y 2
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,z=3 and the xz-plane with y≤0. For each of the following, decide (without calculating its value) whether the integral is positive, negative, or zero. (a) ∫ W 2
​
​
yzdV is (b) ∫ W 1
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​
x 2
ydV is (c) ∫ W 2
​
​
xzdV is