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If `f(x)=cos(log x), " then " f(x)*f(y)-(1)/(2)[f((x)/(y))+f(xy)]` has the valueA. -1B. `(1)/(2)`C. -2D. None of these |
Answer» Correct Answer - D Given, `f(x)=cos(logx)` ` therefore f(x)*f(y)-(1)/(2)[f((x)/(y))+f(xy)]` `=cos(logx)*cos(log y)-(1)/(2) [cos(logx-log y)+cos(logx+log y)]` `=cos(logx)*cos(log y)-(1)/(2)[(2 cos(logx)*cos(logy)]` `=cos (logx)*cos(logy)-cos(logx)*cos(logy)=0` |
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