unit 1/2 quadratics application question

[elpistachio107]

j

[fun_jirachi]

Welcome to the forums!

Note that this isn't actually a question that involves a quadratic in any way (unless you count the solution? - which seems to have a typo) - the most likely quadratic application would be maximising the size of this container.

In general, for some rectangular prism with dimensions \(b \times h \times l\), it will have surface area \(2(bh + hl + lb)\). This won't be the case if the prism is open (in which case you'll need to adjust accordingly).
In this case, simplifying \(2\left((2x-3)\left(\frac{15}{4}-x\right) + \left(\frac{15}{4}-x\right)(15-2x) + (15-2x)(2x-3)\right)\) should do the trick - think your answer should actually be \(-8x(x-6)\).

Hope this helps