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Match List-I with List-II

List-IList-II
Differential equationIntegrating factor
(A) xdydx−y=2x2x\frac{dy}{dx} - y = 2x^2(I) e−ye^{-y}
(B) dydx+yx=2x\frac{dy}{dx} + \frac{y}{x} = 2x(II) 1x\frac{1}{x}
(C) xdydx+2y=x2logxx\frac{dy}{dx} + 2y = x^2logx(III) xx
(D) dxdy−x=y\frac{dx}{dy} - x = y(IV) x2x^2

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 3

For a differential equation in the form dydx+P(x)⋅y=Q(x)\frac{dy}{dx} + P(x) \cdot y = Q(x), the integrating factor is IF=e∫P(x)dxIF = e^{\int P(x)dx}.


(A) xdydx−y=2x2x\frac{dy}{dx} - y = 2x^2

Dividing by xx:

dydx−yx=2x\frac{dy}{dx} - \frac{y}{x} = 2x

Here P(x)=−1xP(x) = -\frac{1}{x}

IF=e∫(−1x)dxIF = e^{\int(-\frac{1}{x})dx}

IF=e−ln⁡∣x∣IF = e^{-\ln|x|}

IF=eln⁡(1x)IF = e^{\ln(\frac{1}{x})}

IF=1xIF = \frac{1}{x}

Match: (A) → (II)


(B) dydx+yx=2x\frac{dy}{dx} + \frac{y}{x} = 2x

The equation is already in standard form.

Here P(x)=1xP(x) = \frac{1}{x}

IF=e∫(1x)dxIF = e^{\int(\frac{1}{x})dx}

IF=eln⁡∣x∣IF = e^{\ln|x|}

IF=xIF = x

Match: (B) → (III)


(C) xdydx+2y=x2log⁡xx\frac{dy}{dx} + 2y = x^2\log x

Dividing by xx:

dydx+2yx=xlog⁡x\frac{dy}{dx} + \frac{2y}{x} = x\log x

Here P(x)=2xP(x) = \frac{2}{x}

IF=e∫(2x)dxIF = e^{\int(\frac{2}{x})dx}

IF=e2ln⁡∣x∣IF = e^{2\ln|x|}

IF=eln⁡(x2)IF = e^{\ln(x^2)}

IF=x2IF = x^2

Match: (C) → (IV)


(D) dxdy−x=y\frac{dx}{dy} - x = y

This equation has dxdy\frac{dx}{dy} instead of dydx\frac{dy}{dx}.

For equations of the form dxdy+P(y)⋅x=Q(y)\frac{dx}{dy} + P(y) \cdot x = Q(y), the integrating factor is IF=e∫P(y)dyIF = e^{\int P(y)dy}.

Rewriting:

dxdy+(−1)⋅x=y\frac{dx}{dy} + (-1) \cdot x = y

Here P(y)=−1P(y) = -1

IF=e∫(−1)dyIF = e^{\int(-1)dy}

IF=e−yIF = e^{-y}

Match: (D) → (I)


The correct matching is:

(A) → (II), (B) → (III), (C) → (IV), (D) → (I)

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