Find the derivative of $x<y<0$ using the definition

Learn how to solve definition of derivative problems step by step online. Find the derivative of x<y<0 using the definition. Find the derivative of x<y<0 using the definition. Apply the definition of the derivative: \displaystyle f'(x)=\lim_{h\to0}\frac{f(x+h)-f(x)}{h}. The function f(x) is the function we want to differentiate, which is x<y<0. Substituting f(x+h) and f(x) on the limit, we get. Cancel like terms x+h<y<0 and -x<y<0. Zero divided by anything is equal to zero. The limit of a constant is just the constant.