Let a curve y=f(x) pass through the points (0,5) and ( e 2,k). If the curve satisfies the differential equation 2(3+y)e2xdx-(7+e2x)dy=0, then k is equal to
- 32
- 8
- 4
- 16
Answer
(2) 8
Solution
Variables separable: y-terms with dy, x-terms with dx.
dy3+y= 2e2x7+e2xdx (numerator = derivative of 7+e2x)
(3+y)= (7+e2x )+ C 3+y=C (7+e2x )
(0,5): 8=8C C=1
x= 2: e2x=4 3+k=11 k=8
Answer: (2)