(a)[2]
Show that $A = 15 + 6x + \dfrac{90}{x}$.
(b)[4]
Graham owns one of these open boxes. The net of his box has total area $65\text{ cm}^2$. Write an equation in $x$ and solve it to determine the length of the base of Graham’s box. Give your answer correct to $2$ decimal places.
(c(i))[1]
Fill in the table below for $A = 15 + 6x + \dfrac{90}{x}$.
(c(ii))[2]
Sketch the graph of $A = 15 + 6x + \dfrac{90}{x}$ for $2 \le x \le 8$.
(c(iii))[2]
Delilah owns one of these open boxes. The area of the net of her box is $68\text{ cm}^2$. Use your graph to determine the length and width of Delilah’s box.