1. A student wants to construct an open box with a base area 35 cm2 from a rectangular piece of cardboard measuring 9 cm by 7 cm.(adsbygoogle = window.adsbygoogle || []).push({});

Find x, where x cm is the length of the side of the square which must be removed from each corner of the cardboard.

this is what i did, i went (9-2x)*(7-2x)=35, then i get it in a form of a quad or cubic, then find the x-intercepts?

2. From a rectangular sheet of metal, ABCD, the part ABP is cut, and the area of the remaining part is 114 cm2.

Find the value of x.

i am totally lost i dont know what to do here

3. The demand, x units of a certain product is given by x = 400 - 0.25p per month

where p is the selling price per unit. The cost, $C, to produce x units is given by

C = 9600 + 1200x

a) Express p in terms of x.

yeah this one i did. p=4 (400 - x)

b) The revenue obtained is a result of selling a number of units at a certain price.

Express the revenue, R, in terms of x.

totally lost, do i just use the x= 400 - 0.25p , and sub p from previous example in?

d) Determine the number of units that must be produced and sold each month :

i) in order to break even

i have to use the c= formula and find the x-intercepts?

ii) if the profit is to be $300 per month.

totally lost here

c) Express the profit, P, in terms of x.

profit... how do i do that?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Applicaitions of cubics + quadratics look at this :p

**Physics Forums | Science Articles, Homework Help, Discussion**