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4 votes
The length of a rectangle is 5 cm longer

than its width. If its area is 36 cm², find its
dimensions.

1 Answer

5 votes

Answer:

From the information given,

Area of rectangle = 36 cm^2

length of rectangle is 5 cm longer than its width

We want to find the length and width of the rectangle

Let W represent the width of the rectangle. It means that

length of rectangle = W + 5

Recall,

Area = length x width

Thus,

W(W + 5) = 36

W^2 + 5W = 36

W^2 + 5W - 36 = 0

This is a quadratic equation. We would solve by applying the method of factorization. The first step is to multiply W^2 with - 36. It becomes – 36W^2. We would find two terms such that their sum or difference is 5W and their product is – 36W^2. The terms are 9W and - 4W By replacing 5W with 9W - 4W, we have

W^2 + 9W - 4W - 36 = 0

Factorize by grouping. It becomes

W(W + 9) - 4(W + 9) = 0

Since W + 9 is common, it becomes

(W + 9)(W - 4) = 0

W + 9 = 0 or W - 4 = 0

W = - 9 or W = 4

Since the width cannot be negative,

W = 4

length = 4 + 5 = 9

Thus, the dimensions are

length = 9 cm

width = 4 cm

Explanation:

The length is a single value

so is the width.

The length cannot be written as a multiplication of two numbers