Square Root Calculation: Finding Side Length of a 400-Unit² Square

A square has an area of 400.

How long are its sides?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the side of the square
00:05 We'll use the formula for calculating the area of a square (side squared)
00:11 We'll substitute appropriate values and solve for the side
00:16 Extract the root
00:21 When extracting a root there are always 2 solutions
00:26 The length of the side must be greater than 0
00:31 And this is the solution to the problem

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

A square has an area of 400.

How long are its sides?

2

Step-by-step solution

The area of the square is equal to the length of the square raised to the second power.

That is:

A=L2 A=L^2

Since we know that the area of the square is equal to 400, we perform the formula as follows:

400=L2 400=L^2

We solve the square root:

400=L \sqrt{400}=L

L=20 L=20

The side of the square is equal to 20.

3

Final Answer

20 20

Practice Quiz

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Look at the square below:

111111

What is the area of the square?

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