Question

The width of a rectangle is the length minus 7 units. The area of the rectangle is 8 units. What is the length, in units, of the rectangle?

Answer 1

The length of the rectangle is equal to 8 units.

Explanation:

Let width be b and length be l.

Width, b = l-7

Area of the rectangle, A = 8 sq units

We need to find the length of the rectangle. The area of a rectangle is given by :

A =lb

So,

`8=l(l-7)\\\\8=l^2-7l\\\\l^2-7l-8=0\\\\l^2-8l+l-8=0\\\\l(l-8)+1(l-8)=0\\\\(l-8)=0\ and\ (l+1)=0\\\\l=8\ and\ l=-1`

So, the value of l is equal to 8 units.