Question

Find a linear second-order differential equation F(x, y, y', y'') = 0 for which y = c1x + c2x4 is a two-parameter family of solutions. Make sure that your equation is free of the arbitrary parameters c1 and c2. (Use yp for y' and ypp for y''.)

Answer 1

Answer:

$4y+ y"x^2-4y'x = 0$

    ↓

$F(x, y, y', y'') = 0$

Step-by-step explanation:

From the information given:

$y = c_1x + c_2x^4 \\ \\ y^1'= c_1 + 4c_2x^3 \\ \\ c_1 =y' - 4c_2x^3$

So;

$y = y'x -4c_2x^4+c_2x^4 \\ \\ y - y'x - 3c_2x^4 \\ \\ y'= y"x+y'- 12c_2x^3 \\ \\ c_2= \dfrac{y"x}{12x^3} \\ \\ c_2= \dfrac{y"}{12x^2}$

∴

$y = y'x- \dfrac{3x^4*y'' }{12x^2} \\ \\ \\ y = y'x - \dfrac{y" x^2}{4} \\ \\ \\ 4y+ y"x^2-4y'x = 0$

  ↓

$F(x, y, y', y'') = 0$