This question is an example of the chain rule for differentiating.
Firstly, identify the inner function. In this case, it is x2 - 3x. This function must be differentiated first:
d/dx (x2 - 3x) = 2x - 3
Secondly, identify the outer function. In this case, it is ez, where z = x2 - 3x. This function must be differentiated second:
d/dz (ez) = ez
The final differentiated result is the derivative of the inner function multiplied by the derivative of the outer function:
dy/dx = (2x - 3)ez = (2x - 3)ex^2 - 3x