Answer
First Derivative: $y'=4x^{2}-1$
Second Derivative: $y''=8x$
Work Step by Step
Using the power rule
First Derivative
$y=\frac{4x^{3}}{3}-x$
$y'=\frac{(4)(3)x^{3-1}}{3}-(1)x^{1-1}$
$y'=4x^{2}-1$
Second Derivative
$y'=4x^{2}-1$
$y''=(4)(2)x^{2-1}-(0)$
$y''=8x$
(the derivative of 1 will be 0 because of the rule of the constant function).