JEE 2022 — Mathematics PYQ
JEE | Mathematics | 2022If y=y(x) is the solution of the differential equation (1+e2x)dxdy+2(1+y2)ex=0 and y(0)=0, then 6(y′(0)+(y(loge3)))2 is equal to:
Choose the correct answer:
- A.
2
(Correct Answer) - B.
-2
- C.
-4
- D.
1
2
Explanation
Step 1: Variable Separation aur Integration
Terms ko separate karne par:
⇒1+y2dy=−1+e2x2exdx
Dono taraf integration karne par:
⇒∫1+y2dy=−2∫1+e2xexdx
⇒tan−1(y)=−2tan−1ex+C
Step 2: Constant C ki value nikalna
Hame pata hai y(0)=0, isliye x=0 aur y=0 rakhne par:
∴tan−1(0)=−2tan−1(1)+C
⇒C=2(4π)=2π
Ab hum solution ko aise likh sakte hain:
⇒tan−1y+2tan−1ex=2π…(i)
Step 3: y′(0) ki value nikalna
Equation se dxdy ki value x=0 par:
Now, (dxdy)x=0=(−1+e2x2(1+y2)ex)x=0
⇒(dxdy)x=0=−1
Step 4: y(loge3) ki value nikalna
Equation (i) mein x=loge3 rakhne par:
tan−1y+2tan−1eloge3=2π
⇒tan−1y+2tan−13=2π
⇒tan−1y+32π=2π
⇒tan−1y=−6π
⇒y(loge3)=−31
Step 5: Final Calculation
Hame iski value nikalni hai:
∴6[y′(0)+y(loge3)2]=6[−1+31]=−4
Final Answer: -4
Explanation
Step 1: Variable Separation aur Integration
Terms ko separate karne par:
⇒1+y2dy=−1+e2x2exdx
Dono taraf integration karne par:
⇒∫1+y2dy=−2∫1+e2xexdx
⇒tan−1(y)=−2tan−1ex+C
Step 2: Constant C ki value nikalna
Hame pata hai y(0)=0, isliye x=0 aur y=0 rakhne par:
∴tan−1(0)=−2tan−1(1)+C
⇒C=2(4π)=2π
Ab hum solution ko aise likh sakte hain:
⇒tan−1y+2tan−1ex=2π…(i)
Step 3: y′(0) ki value nikalna
Equation se dxdy ki value x=0 par:
Now, (dxdy)x=0=(−1+e2x2(1+y2)ex)x=0
⇒(dxdy)x=0=−1
Step 4: y(loge3) ki value nikalna
Equation (i) mein x=loge3 rakhne par:
tan−1y+2tan−1eloge3=2π
⇒tan−1y+2tan−13=2π
⇒tan−1y+32π=2π
⇒tan−1y=−6π
⇒y(loge3)=−31
Step 5: Final Calculation
Hame iski value nikalni hai:
∴6[y′(0)+y(loge3)2]=6[−1+31]=−4
Final Answer: -4

