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

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Sec 8]_The Lagrange and Clairaut Equations_339<br />

2814. yy'*(xy+l)y' + x = Q.<br />

2<br />

2815. yij' 2xy'+y = Q.<br />

2816. F<strong>in</strong>d the <strong>in</strong>tegral curves of the equation y'* +y* = 1<br />

that pass through the po<strong>in</strong>t M ( 0, y )<br />

Introduc<strong>in</strong>g the parameter y' = p, solve the equations:<br />

2817. x=smy'+lny'. 2820. 4y = x*+y'\<br />

2818. y = 2 /2<br />

y'*e>". 9 91<br />

,*<br />

'<br />

2819. = y'*<br />

Sec. 8. The Lagrange and Clairaut Equations<br />

1. Lagrange's equation. An equation of the form<br />

= *(P), (1)<br />

where p = tf is called Lagrange's equation Equation (1) is reduced to a l<strong>in</strong>ear<br />

equation <strong>in</strong> x by differentiation and tak<strong>in</strong>g <strong>in</strong>to consideration that dy^pdx:<br />

.<br />

f<br />

(p)] dp. (2)<br />

If p^q>(p), then from (1) and (2) we get the general solution <strong>in</strong> parametric<br />

form:<br />

where p is a parameter and f(p)^ g(p) are certa<strong>in</strong> known functions. Besides,<br />

there may be a s<strong>in</strong>gular solution that is found <strong>in</strong> the usual way.<br />

2. C'lairaut's equation. If <strong>in</strong> equation (l)p^

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