PUC Karnataka Science Class 12Department of Pre-University Education, Karnataka
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Solution for If X = At2, Y = 2 At, Then D 2 Y D X 2 = (A) − 1 T 2 - PUC Karnataka Science Class 12 - Mathematics

ConceptSimple Problems on Applications of Derivatives

Question

If x = at2, y = 2 at, then $\frac{d^2 y}{d x^2} =$

(a) $- \frac{1}{t^2}$

(b) $\frac{1}{2 \ at^3}$

(c) $- \frac{1}{t^3}$

(d) $- \frac{1}{ 2 \ at^3}$

Solution

(d) $- \frac{1}{2 \ a t^3}$

$x = a t^2 \text { and y } = 2\text { at }$
$\text { Differentiating w . r . t . t, we get }$
$\frac{d x}{d t} = 2\text { at and } \frac{d y}{d t} = 2a$
$\therefore \frac{d y}{d x} = \frac{2a}{2at} = \frac{1}{t}$
$\text{ Differentiating again w . r . t . t, we get }$
$\frac{d^2 y}{d x^2} = \frac{- 1}{t^2}\frac{d t}{d x} = \frac{- 1}{2 \ a t^3}$

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Solution If X = At2, Y = 2 At, Then D 2 Y D X 2 = (A) − 1 T 2 Concept: Simple Problems on Applications of Derivatives.
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