Question

A box has a volume of 308 cm cubed. Its height is 4 cm greater than its length. Its length is 3 cm greater than its width. What is the width of the box? SHOW YOUR WORK.

Answer 1

Answer:

4 cm.

Step-by-step explanation:

Given:

A box has a volume of 308 cm cubed.

Its height is 4 cm greater than its length.

Its length is 3 cm greater than its width.

Question asked:

What is the width of the box?

Solution:

Let width  = $x\ cm$

Length = $x+3\ cm$

Height = $x+3+4=x+7\ cm$

As we know:

$Volume\ of\ box=length\times width\times height$

$308=(x+3)\times x\times(x+7)\\ \\ 308=(x^{2} +3x)(x+7)\\ \\ 308=x^{2} (x+7)+ 3x(x+7)\\ \\ 308=x^{3} +7x^{2} +3x^{2} +21x\\ \\ 308=x^{3} +10x^{2} +21x\\ \\ Subtract\ 308\ from\ both\ sides\\ \\ x^{3} +10x^{2} +21x-308=0\\ \\ factor\ left\ side\ of\ equation\\ \\ (x-4)(x^{2} +14x+77)=0\\ \\ Set\ factors\ equal\ to\ 0.\\ \\ x-4=0 \ or\ x^{2} +14x+77=0$

As width can never be in negative, $x= 4\ cm$

By substituting the value:-

Width  = $x\ cm$ = 4 cm

Thus, width of the box is 4 cm.