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Problems in Mathematical Analysis.pdf - pwp.net.ipl.pt

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Sec. 1] The Double Integral <strong>in</strong> Rectangular Coord<strong>in</strong>ates 247<br />

be computed by reduc<strong>in</strong>g to an iterated <strong>in</strong>tegral by the formula<br />

(S)<br />

*a yi), and from the left and the<br />

right by the cont<strong>in</strong>uous curves x = ^> l (y) (AB) and x = i|? 2 (y) (CD) [t|? 2 (y) ^ ^ (y)],<br />

each of which <strong>in</strong>tersects the parallel y = Y (y* ^ Y < y t) at only one po<strong>in</strong>t<br />

(Fig. 86).<br />

As before, we have<br />

Vl $2 (U)<br />

JJ/(*. y)dxdy=\dy J<br />

(S) j/i i|?, ((/)<br />

f (x. y)dx t<br />

here, <strong>in</strong> the <strong>in</strong>tegral \ f(x, y) dx we consider y constant.<br />

If the region of <strong>in</strong>tegration does not belong to any of the above-discussed<br />

types, then an attem<strong>pt</strong> is made to break it up <strong>in</strong>to parts, each of which does<br />

belong to one of these two types.<br />

Example 1. Evaluate the <strong>in</strong>tegral<br />

Solution.<br />

/<br />

Example 2. Determ<strong>in</strong>e the limits of <strong>in</strong>tegration of the <strong>in</strong>tegral<br />

(S)<br />

D<br />

(x, y)dxdy

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