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JEE Advanced 2025Paper 1
Exam
JEE Advanced
Year
2025
Paper
Paper 1
Subject
Mathematics
Chapter
Differential Equations

JEE Advanced 2025 · Paper 1 · Mathematics · Differential Equations

For all x>0 , let y_1(x), y_2(x) , and y_3(x) be the functions...

For all x>0x>0, let y1(x),y2(x)y_1(x), y_2(x), and y3(x)y_3(x) be the functions satisfying dy1dx−(sin⁡x)2y1=0,y1(1)=5dy2dx−(cos⁡x)2y2=0,y2(1)=13dy3dx−(2−x3x3)y3=0,y3(1)=35e\begin{aligned} & \frac{d y_1}{d x}-(\sin x)^2 y_1=0, y_1(1)=5 \\ & \frac{d y_2}{d x}-(\cos x)^2 y_2=0, y_2(1)=\frac{1}{3} \\ & \frac{d y_3}{d x}-\left(\frac{2-x^3}{x^3}\right) y_3=0, y_3(1)=\frac{3}{5 e}\end{aligned} respectively. Then lim⁡x→0+y1(x)y2(x)y3(x)+2xe3xsin⁡x\lim _{x \rightarrow 0^{+}} \frac{y_1(x) y_2(x) y_3(x)+2 x}{e^{3 x} \sin x} is equal to _____

Correct answer

0

Step-by-step solution

dy1y1+dy2y2+dy3y3=(sin⁡2x+cos⁡2x+2−x3x3)dxln⁡(y1y2y3)=−1x2+Cln⁡(y1(x)y2(x)y3(x))=−1x2+Cln⁡(5⋅13⋅35e)=−1x2+C∴C=0\begin{aligned} & \frac{d y_1}{y_1}+\frac{d y_2}{y_2}+\frac{d y_3}{y_3}=\left(\sin ^2 x+\cos ^2 x+\frac{2-x^3}{x^3}\right) d x \\ & \ln \left(y_1 y_2 y_3\right)=\frac{-1}{x^2}+C \\ & \ln \left(y_1(x) y_2(x) y_3(x)\right)=\frac{-1}{x^2}+C \\ & \ln \left(5 \cdot \frac{1}{3} \cdot \frac{3}{5 e}\right)=\frac{-1}{x^2}+C \\ & \therefore C=0\end{aligned}y1(x)y2(x)y3(x)=e−1x2lim⁡x→0e−1x2+2xe3xsin⁡xlim⁡x→01e3x+1x2sin⁡x+lim⁡x→02xe3xsin⁡x\begin{aligned} & y_1(x) y_2(x) y_3(x)=e^{\frac{-1}{x^2}} \\ & \lim _{x \rightarrow 0} \frac{e^{\frac{-1}{x^2}}+2 x}{e^{3 x} \sin x} \\ & \lim _{x \rightarrow 0} \frac{1}{e^{3 x+\frac{1}{x^2}} \sin x}+\lim _{x \rightarrow 0} \frac{2 x}{e^{3 x} \sin x}\end{aligned} \lim _{x \rightarrow 0} \frac{1}{e^{3 x} \cdot \frac{\sin x}{x} \cdot \frac{e^{\frac{1}{x^2}}}{\frac{1}{x}}}+2 =0+2 \quad\left\{\lim _{\mathrm{y} \rightarrow \infty} \frac{\mathrm{e}^{\mathrm{y}^2}}{\mathrm{y}}=\frac{\mathrm{e}^{\mathrm{y}^2} \cdot 2 \mathrm{y}}{1}=\infty\right\} =2$
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