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

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186 Functions of Several Variables [Ch. 6<br />

A rational <strong>in</strong>tegral function will be homogeneous if all its terms are of one<br />

and the same degree.<br />

The follow<strong>in</strong>g relationship holds for a homogeneous differentiable function<br />

of degree n (Euler's theorem):<br />

xfx (x, y) + yfy (x, y) = nf (x, y).<br />

F<strong>in</strong>d the partial derivatives of the follow<strong>in</strong>g functions:<br />

1801. z = 3axy. 1808. 2 =<br />

1809. 2 =<br />

1806.<br />

1807. z = arc tan<br />

1810. 2 =<br />

1811. 2 =<br />

1814. F<strong>in</strong>d /;(2, 1) and fy (2, 1) if f(x,y)<br />

1815. F<strong>in</strong>d /;(!, 2, 0), /i(l, 2, 0), ft (l, 2, 0) if<br />

/(*, y,z) = ln(xy-\-z).<br />

xy+L .<br />

Verify Euler's theorem on homogeneous functions <strong>in</strong> Examples<br />

1816 to 1819:<br />

1816. f(x,y) = Ax 3<br />

+ 2Bxy-Cy t . 1818. /<br />

1817. z =<br />

1820. J-<br />

) , where r = :<br />

2<br />

1821. Calculate<br />

1822. Show that<br />

1823. Show that x+<br />

and y<br />

57, = 2, if 2 = ln(*'<br />

, if 2 =<br />

1824. Show that g+fj+S-0, if u = (x-y)(y-z)(z- X ).<br />

1825. Show that g+g+g-1, if<br />

J826. F<strong>in</strong>d -.(,. y), it<br />

-*+J=J.

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