## calyne 2 years ago Find y'' by implicit differentiation: 9x^2+y^2 = 9

1. robtobey
2. Dockworker

messed up the quotient rule...sigh

3. calyne

...

4. eigenschmeigen

$9x^2 +y^2 =9$ $\text{ } 18x +2y(dy/dx) = 0$ $dy/dx=-(18x/2y)$ $18 +2(dy/dx) + 2y(d^2y/dx^2) =0$ $d^2y/dx^2 = -(18 + 2(dy/dx))/2y$ now sub in dy/dx $d^2y/dx^2 = -(18 - 2(18x/2y))/2y = 36(x - y)/(2y)^2$

5. eigenschmeigen

no need for the quotient rule with that method