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Exercicios resolvidos James Stewart vol. 2 7ª ed - ingles

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SECTION 16.5 CURL AND DIVERGENCE 0 319<br />

ForExercises23-29, 1etF(x,y,z) = P1 i+ Qd + R1 ~and G(x,y,z) = P2 i + Q2j + R2 k.<br />

23. div(F +G)= div(Pt + P2 , Q1 + Qz,R1 + R 2 ) = o(P 1 0 + P2 ) + o(Q 1 0 + Qz )" + o(R1 / R 2 )<br />

• X y Z<br />

= oP1 + oPz + oQ1 + oQ2 + oR1 + oR2 = (oP1 + oQ1 + oR1) + ( oP2 + oQ2 + oR2)<br />

ox ox oy oy o z o z ox oy o z ox oy o z<br />

= div(P1 ,,Q1, R1) + div(Pz , Qz , Rz ) = div F + div G<br />

27. div(F X G) ='iJ · (F x G)=<br />

= [Q 1<br />

oR2 + R 2<br />

oQ1 _ Q 2 oR1 _ R 1 oQ2] _ [p 1<br />

oRz + Rz oP1 _ Pz oR1 _ R 1<br />

oPz]<br />

ox ox ox ox .oy oy ay ay<br />

+ [Pt oQ2 + Q 2<br />

oP1 _ p 2 oQ1. _ Q 1<br />

oP2 ]<br />

oz oz . oz oz<br />

= [p 2 (oR1 _ oQ1) +Q 2 (oP1 _ oR1) +Rz(oQ1 _ 8P1 )]<br />

oy oz oz ox OX ay<br />

_ [p 1<br />

(oRz _ oQz) -f_ Q 1<br />

(oP2 _ oRz) + R 1 (oQz ~ aP2 )]<br />

oy az az ox ox 8y<br />

= G · curl F - F · curl G<br />

j<br />

29. curl{ curl F) = 'iJ x ('iJ x F) = ajax a;ay<br />

k<br />

a;az<br />

Now let's consider grad(div F ) - 'iJ 2 F and compare with the above.<br />

(Note that 'iJ 2 F is defin<strong>ed</strong> 'on page J J 19 [ET I 095).)<br />

[continu<strong>ed</strong>]<br />

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