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8. Sequences and Series
medium
यदि $f(x + y,x - y) = xy\,,$ तब $f(x,y)$ और $f(y,x)$ का समांतर माध्य होगा
A
$x$
B
$y$
C
$0$
D
$1$
Solution
(c) माना $x + y = u,\,\,x – y = v$
$x = \frac{{u + v}}{2},y = \frac{{u – v}}{2}$
$\therefore f(u,v) = \left( {\frac{{u + v}}{2}} \right).\left( {\frac{{u – v}}{2}} \right)$
$\therefore \frac{{f(x,y) + f(y,x)}}{2} = \frac{{\frac{{u + v}}{2}.\frac{{u – v}}{2} + f\left( {\frac{{u + v}}{2}.\frac{{v – u}}{2}} \right)}}{2} = 0$
Standard 11
Mathematics