Find the derivative: Do I use the Quotient Rule, Product Rule, or Chain Rule? I have to find the derivative of:
$$y=\frac{(5x^6-1)}{x^2}$$
I keep on getting this problem wrong. Should I use the quotient rule 
$$\frac{f(x)g'(x) - g(x)f'(x)}{g(x)^2}$$
However, my answer is:
$$y'= 30x^2 +\frac{6}{x^4} - 120{x^3}$$
Am I utilizing the wrong method, or have I just evaluated the problem incorrectly? 

$$\frac{dy}{dx}=\frac{(5x^6-1)'x^2-(5x^6-1) (x^2)'}{x^4}=\frac{30x^5 \cdot x^2-2x(5x^6-1)}{x^4}=\frac{30x^7-10x^7+2x}{x^4}=\frac{20x^7+2x}{x^4}=20x^3+\frac{2}{x^3}$$
