Question 1 - A-Level Maths

Exam Board	Edexcel
Module	AS Paper 1 (AS Paper 1)
Year	2023
Session	June
Topic	Differentiation Applications
Type	Increasing/decreasing intervals

$$y = \frac { 2 } { 3 } x ^ { 3 } - \frac { 7 } { 2 } x ^ { 2 } - 4 x + 5$$

Find $\frac { \mathrm { d } y } { \mathrm {~d} x }$ writing your answer in simplest form.
Hence find the range of values of $x$ for which $y$ is decreasing.