Answer
The derivative is $8x+3$.
Work Step by Step
To start solving this problem you must first split the numerator.
A note worth mentioning is that $\frac{a+b}{c}=\frac{a}{c}+\frac{b}{c}$ but $\frac{a}{b+c}\ne\frac{a}{b}+\frac{a}{c}$. Keeping this straight would help you avoid making mistakes and simplifying calculations.
By splitting we get $y = \frac{4x^3}{x}+\frac{3x^2}{x} = 4x^2+3x$.
To differentiate, just differentiate the individual terms using the power rule $((x^n)' = nx^{n-1})$. The derivative of $4x^2$ is $8x$ while the derivative of $3x$ is $3$. This gives us $y' = 8x+3$.
