If the solution y=y(x) of the differential equation (x4+2x3+3x2+2x+2 )dy- (2x2+2x+3 )dx=0 satisfies y(-1)=- 4, then y(0) is equal to :
- - 12
- 2
- 0
- 4
Answer
(4) 4
Solution
x4+2x3+3x2+2x+2=(x2+1)(x2+2x+2) and 2x2+2x+3=(x2+1)+(x2+2x+2)
dydx= 1x2+2x+2+ 1x2+1= 1(x+1)2+1+ 1x2+1
y= -1(x+1)+ -1x+C
y(-1)=0- 4+C=- 4 C=0
y(0)= -11+0= 4
Answer: (4)