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CBSE Class 12 Math 2013 Solved Paper

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Question : 14 of 29
Marks: +1, -0
Differentiate the following function with respect to x:
(logx)π+xlogπ(logx)^π + x^{logπ}
Solution:  
Let y = (logx)π+xlogπ(logx)^π + x^{logπ} ... (1)
Now let y1y_1 = (logx)x(logx)^x and yz = xlogxx^{logx}
⇒ y = y1+y2y_1+y_2 ... (2)
Differentiating (2) w.r.t. x,
dy/dx{dy}/{dx} = dy1/dx+dy2/dx{dy_1}/{dx}+{dy_2}/{dx} ... (3)
Now consider y1y_1 = (logx)π(logx)^π
Taking log on both sides,
log y1y_1 = x log (log x)
Differentiating w.r.t. x, we get
1/y1dy1/dx1/y_1 {dy_1}/{dx} = x × 1/logx1/{logx} × 1/x1/x + 1 - log (log x)
dy1/dx{dy_1}/{dx} = y1(1/logx+log(logx))y_1(1/{logx} + log(logx))
dy1/dx{dy_1}/{dx} = logxπ(1/logx+log(logx))log x^π (1/{logx} + log (logx)) ... (4)
⇒ Now, consider y2y_2 = (log x) (log x) = (logx)2(logx)^2
Differentiating w.r.t. x, we get
1/y2dy2/dx1/y_2 {dy_2}/{dx} = 2 log x × 1/x1/x
dy2/dx{dy_2}/{dx} = y2(2logx/x)y_2 ({2logx}/x) = xlogx(2logx/x)x^{logx} ({2logx}/x) ... (5)
Using equations (3), (4) and (5), we get:
dy/dx{dy}/{dx} = logxπ(1/logx+log(logx))logx^π(1/{logx}+log(logx)) + xlogπ(2logx/x)x^{logπ}({2logx}/x)
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