In each of the question, form a differential equation representing the given family of curves by eliminating arbitrary constants a and b.
y = e2x (a + bx)
It is given y = e2x(a + bx) -------(1)
Now, differentiating both side w.r.t. x, we get,
y’ = 2e2x(a + bx) + e2x.b ------(2)
Now, let us multiply equation (1) with 2 and then subtracting it to equation (2), we get,
y’ – 2y = e2x(2a +2bx + b) – e2x(2a + 2bx)
⇒ y’ – 2y = be2x ---------(3)
Now, again differentiating both sides w.r.t. x, we get,
y” – 2y’ = 2be2x ------(4)
Dividing equation (4) by equation (3), we get,
⇒ y” – 2y’ = 2y’ – 4y
⇒ y” – 4y’ – 4y = 0
Therefore, the required differential equation is y” – 4y’ - 4y = 0.