Question
Find $\frac{d y}{d x}$ if, :
$
y=\sqrt{x+\frac{1}{x}}
$

Answer

Given : $y=\sqrt{x+\frac{1}{x}}$
Let $u=x+\frac{1}{x}$
Then $y=\sqrt{u}$
$
\therefore \frac{d y}{d u}=\frac{d}{d u}\left(u^{\frac{1}{2}}\right)=\frac{1}{2} u^{-\frac{1}{2}}
$
$
=\frac{1}{2 \sqrt{u}}=\frac{1}{2 \sqrt{x+\frac{1}{x}}}
$
$
\text { and } \begin{aligned}
\frac{d u}{d x} & =\frac{d}{d x}\left(x+\frac{1}{x}\right) \\
& =\frac{d}{d x}(x)+\frac{d}{d x}\left(x^{-1}\right) \\
& =1+(-1) x^{-2}=1-\frac{1}{x^2}
\end{aligned}
$
$
\begin{aligned}
\therefore \frac{d y}{d x} & =\frac{d y}{d u} \cdot \frac{d u}{d x}=\frac{1}{2 \sqrt{x+\frac{1}{x}}} \cdot\left(1-\frac{1}{x^2}\right) \\
& =\frac{1}{2}\left(x+\frac{1}{x}\right)^{-\frac{1}{2}}\left(1-\frac{1}{x^2}\right) .
\end{aligned}
$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Evalute : $\int(\log x)^2 d x$
Obtain the differential equation by eliminating arbitrary constants from the following equations : $y=\left(c_1+c_2 x\right) e^x$
10 balls are marked with digits 0 to 9. If four balls are selected with replacement. What is the probability that none is marked 0?
A doctor has prescribed two different kinds of feeds A and B to form a weekly diet for a sick person. The minimum requirement of fats, carbohydrates, and proteins are 18, 28,14 units respectively. One unit of food A has 4 units of fat, 14 units of carbohydrates, and 8 units of protein. One unit of food B has 6 units of fat, 12 units of carbohydrates and 8 units of protein. The price of food A is ₹ 4.5 per unit and that of food B is ₹ 3.5 per unit. Form the LPP so that the sick person’s diet meets the requirements at minimum cost.
Construct a matrix $A =\left[ a _{ i j}\right]_{3 \times 2}$ whose elements aij isgiven by : $a_{ij} = i – 3j$
Calculate the cost of living index.
Group Food Clothing Fuel & Lighting House Rent Miscellaneous
I 200 150 120 180 160
W 30 20 10 40 50
Solve the following differential equations : $\frac{d y}{d x}=x^2 y+y$
Prepare the truth tables for the following statement patterns : p → (~p ∨ q)
Rewrite the following statements without using conditional:
[Hint: P → q ≡ ~p ∨ q]
(i) If price increases, then demand falls.
(ii) If demand falls, then the price does not increase.
Calculate the cost of living index.
GroupBase YearBase YearCurrent Year
PriceQuantityPrice
Food401545
Clothing301035
Fuel & Lighting201725
House Rent602270
Miscellaneous702580