If the Solution y = y(x) of the differential equation (x4+2x3+3x2+2x+2)dy-(2x2+2x+3)dx=0 satisfies y(-1)=-π4, then y(0) is equal [2024]
(1)
(x4 + 2x3 + 3x2 + 2x + 2)dy - (2x2 + 2x + 3)dx = 0
dydx = 2x2 + 2x + 3x4 + 2x3 + 3x2 + 2x + 2
⇒ ∫dy = ∫ (2x2 + 2x + 3x4 + 2x3 + 3x2 + 2x + 2) dx
⇒ ∫dy = ∫2x2 + 2x + 3(x2 + 1)(x2 + 2x + 2) dx
⇒ ∫dy = ∫1x2 + 1 dx + ∫1(x + 1)2 + 1 dx
⇒ y = tan-1(x) + tan-1(1 + x) + C ... (i)
Now, y(-1) = -π4
∴ From (i), we get -π4 = tan-1(-1) + tan-1(1 - 1) + C
⇒ -π4 = - π4 + C ⇒ C = 0
So, y(x) = tan-1(x) + tan-1(1 + x)
Now, y(0) = tan-1(0) + tan-1(1 + 0) = π4.