Exercise 5.7 - Chapter 5 - Differential Calculus - 11th Business Maths Guide Samacheer Kalvi Solutions
Updated On 26-08-2025 By Lithanya
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Exercise 5.7
Text Book Back Questions and Answers
Question 1.
Differentiate the following with respect to x.
(i) xsin x
(ii) (sin x)x
(iii) (sin x)tan x

Solution:
(i) Let y = xsin x
Taking logarithm on both sides we get,
log y = log(xsin x)
log y = sin x log x
Differentiating with respect to x,

(ii) Let y = (sin x)x
Taking logarithm on both sides we get,
log y = x log(sin x)
Differentiating with respect to x,

(iii) Let y = (sin x)tan x
Taking logarithm on both sides we get,
log y = tan x log(sin x)
Differentiating with respect to x,


Taking logarithm on both sides we get,
log y = 1/2 {[log(x – 1) + log(x – 2)] – [(log(x – 3) + log(x2 + x + 1)]}
log y = 1/2 [log(x – 1) + log(x – 2) – log(x – 3) – log(x2 + x + 1)]
Differentiating with respect to x,

Question 2.
If xm . yn = (x + y)m+n, then show that 
Solution:
xm . yn = (x + y)m+n
Taking logarithm on both sides we get,
m log x + n log y = (m + n) log(x + y)
Differentiating with respect to x,

Hence proved.
