Question

A rectangle has length x and width x – 3. The area of the rectangle is 10 square meters. Complete the work to find the dimensions of the rectangle. x(x – 3) = 10 x2 – 3x = 10 x2 – 3x – 10 = 10 – 10 (x + 2)(x – 5) = 0 What are the width and length of the rectangle?

Answer 1

Explanation:

Area of rectangle = Length × Width

The given rectangle has a length if x meters

The width of the triangle is (x-3) meters

The area of the rectangle is given as 10 square meters.

Area if rectangle = x(x-3) = 10

Multiplying each term in the parentheses,

x^2 -3x = 10

x^2 -3x -10 = 0

This is a quadratic equation

We will look for two numbers such that when they are multiplied, it will give us -10x^2 and when they are added, it will give -3x. It becomes

x^2 + 2x - 5x -10 = 0

x(x+2)-5(x+2) =0

( x + 2)(x-5) = 0

x = -2 or x = 5

The length of the rectangle cannot be negative so the length is 5 meters

Widith = x+3 = 5-3 = 2 meters