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

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Cha<strong>pt</strong>er VII<br />

MULTIPLE AND LINE INTEGRALS<br />

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

1. Direct computation of double <strong>in</strong>tegrals. The double <strong>in</strong>tegral of a cont<strong>in</strong>uous<br />

function f (x, y) over a bounded closed region S is the limit of the<br />

correspond<strong>in</strong>g two-dimensional <strong>in</strong>tegral sum<br />

f (x, y)dx dy = lim<br />

max A*i -<br />

max Ar//c -<br />

- where A* = t Xf +l xg, &yk = yk+l yk and the sum is extended over those<br />

values of i and k for which the po<strong>in</strong>ts (*/, yk ) belong to S.<br />

2. Sett<strong>in</strong>g up the limits of <strong>in</strong>tegration <strong>in</strong> a double <strong>in</strong>tegral. We dist<strong>in</strong>guish<br />

two basic types of region of <strong>in</strong>tegration.<br />

x,<br />

x<br />

Fig. 85<br />

o<br />

Fig. 86<br />

1) The region of <strong>in</strong>tegration 5 (Fig. 85) is bounded on the left and right<br />

Fig. 85). In the region S, the variable x varies from x l to x while the variable<br />

y (for x constant) varies from ^ = 9, (x) to j/2 = q> 2 (x). The <strong>in</strong>tegral (1) ma><br />

(1)

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