Let y=y(x) be the solution of the differential equation (1-x2 )dy= [xy+ (x3+2 ) 3 (1-x2 ) ]dx, -1<x<1, y(0)=0. If y ( 12 )= mn, m and n are co-prime numbers, then m+n is equal to .
Answer
97
Solution
dydx- x1-x2 y= 3 (x3+2 ) 1-x2 (linear in y)
I.F. =e- x1-x2dx=e 12 (1-x2 )= 1-x2
y 1-x2= 3 (x3+2 )dx= 3 ( x44+2x )+c
y(0)=0 c=0
x= 12: y 32= 3 ( 164+1 ) y= 6532
m+n=65+32=97
Answer: 97