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Last updated on October 22, 2025

X Squared

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The term ‘x squared’ refers to the expression x2, where x is multiplied by itself. In this article, we will learn more about squaring and its applications in real life.

X Squared for US Students
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What is X Squared?

In algebra, when x is multiplied by itself, it is written as x2. Here, x is the base and 2 is its exponent. In other words, for any variable x, x2 is an algebraic notation that refers to a number being multiplied by itself i.e., x . x=x2
 

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How to Find the Value of x2?

The value of x2 can be found by multiplying the value of x with itself.
Let us take a few examples to see how:
Example 1. If x = 3
x2 = 3 × 3 = 9

Example 2: If x = - 4
x2 = (- 4) × (- 4) = 16


Example 3: If x = 0
x2 = 0 × 0 = 0

Example 4. If x = 1.5
x2 = 1.5 × 1.5 = 2.25

Example 5. If x = 2/5
x2 = (2/5)×(2/5)=4/5

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What are Perfect Squares?

Perfect squares are products of an integer multiplied by itself. So, if x is an integer, then x2 is a perfect square.
Given below is a chart of the first 50 perfect squares for your reference.
 

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Square Root of x

The square root of a variable x is the number that, upon multiplying by itself, gives x as the product. It is written as √x. The square root of x2  is |x| because x × x=(-x) × (-x)=x2
So, √x2 = x or x
For example, if x = - 7
√x2 =√(-7)2 =√49 =7=7 or 7

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Is x Squared the Same as 2x?

x squared and 2x do not mean the same thing. In x2, x is the base and 2 is the exponent. In 2x, 2 is the coefficient of x, indicating that x is multiplied by 2. 
For example, If x = 11, 
then x2 = x × x = 11 × 11 = 121, and 
2x = 2 × x = 2 × 11 = 22

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What is the Sum of Squares and Difference of Squares?

The sum of squares can be found using the formula,
 a2+b2=(a+b)2-2ab
For instance, let’s take a = 3 and b = 4,
Substituting the values in the formula provided above, we get,
32 + 42 = (3 + 4)2 - 2(3)(4)
= 49 - 24
= 25

To find the difference of squares, we use the formula,
a2-b2=(a+b)(a-b) 
Let’s assume that a is 6 and b is 2
Substituting the values, we get,
62 - 22 = (6 + 2)(6 - 2) 
= 8 × 4
= 32
 

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What is the Difference between Two Perfect Squares?

The formula for the difference of two perfect squares helps simplify complex algebraic expressions. It is useful while writing algebraic expressions as factors.
Let’s say there are two numbers x and y. To calculate the difference of their squares, we use the formula,
x2 - y2 = (x + y)(x - y)
Let us take x = 2 and y = 7
22 - 72 = (2 + 7)(2 - 7)
= 9 × (-5)
= -45

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How to Solve Quadratics by Completing the Square?

Completing the square refers to expressing a quadratic expression ax2 + bx + c as a(x + d)2 + e.
Where
a is the coefficient of x2 from the original expression.
d comes from b/2a, so (x + d)2 is the part that is being completed.
e is the adjustment constant added to balance the expression after completing the square. It is calculated as e = c - a(b/2a)2 =c-b2/4a.
For example, let’s complete the square for 2x2 + 8x + 5
Step 1: Factor out the coefficient of x2
= 2(x2 + 4x) + 5
Step 2: Complete squaring inside parentheses 
42= 2, 22 = 4
Now add and subtract 4 inside the parentheses
= 2(x2 + 4x + 4 - 4) + 5 
= 2((x + 2)2 - 4) + 5 
= 2(x + 2)2 - 8 + 5 
= 2(x + 2)2 - 3

The completed square form of 2x2 + 8x + 5 is 2(x + 2)2 - 3
Here, a = 2, d = 2 and e = - 3.
 

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Common Mistakes and How to Avoid Them in X Squared

Students might make small mistakes that may go unnoticed while finding solutions related to x2. Although trivial, these mistakes can lead to incorrect answers. Given below is a list of a few such errors and tips to avoid them.

Mistake 1

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 Forgetting that (- x)2 = x2
 

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Even if negative numbers are being squared, the results will always be positive. For example, (-3)2 = -9 is incorrect; the answer will be (-3)2 = 9.

Mistake 2

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Assuming x2 =2x
 

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x2 and 2x are not the same; the exponent means multiplying the number by itself and not by 2.
 

Mistake 3

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Applying the difference of squares identity for the sum of squares

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There is no identity for a2 + b2, and sometimes students apply a2 - b2 = (a + b)(a - b), which is incorrect.

Mistake 4

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Squaring a binomial incorrectly.

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Students apply incomplete expansion while squaring a binomial. For instance, (x + y)2 = x2 + 2xy + y2, but students leave it at (x + y)2 = x2 + y2 which is incomplete.

Mistake 5

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Assuming that a square root is always positive

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The square root of a non-negative number x is non-negative (√x  0), not always positive, since 0 = 0. For √x2, it's x, not |x|, because the result must be non-negative.   

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Real-life Applications of X Squared

X squared as a mathematical concept has many real-life applications. From architecture to astronomy, x squared is used in many fields, some of which are discussed here:

  • Area of a square: For a square with a side x, its area is x2. This is helpful in area related problems in geometry and architecture.

 

  • Formula for kinetic energy : In physics, kinetic energy is calculated as KE = 12mv2, where v2 is the square of the object’s speed. This helps in understanding motion, designing vehicles, and improving crash safety.  

 

  • Projectile motion: When we throw a football, the distance traveled and height achieved can be modeled using squared terms of time and velocity. This helps athletes, engineers, and game designers predict how things move through the air.

 

  • Stress and strain calculations: In engineering/material science, stress and strain involve squared terms to model deformation under weight accurately.

 

  • Satellite and signal coverage: To find the area a satellite or signal can cover, we use the formula for the area of a circle: A = r2. This is useful in planning GPS coverage, Wi-Fi range, and telecom networks.
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Solved Examples of X Squared

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Problem 1

If x = 5, what is the value of x2?

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25
 

Explanation

 x2 = 52 = 5 × 5 = 25
 

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Problem 2

If x2 = 100, what is the value of x?

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x =  10
 

Explanation

If x2 = 100, then taking the square roots of both sides we get,

√x2 = √100 = 10.

The answer is both positive and negative because both (10)2 and (-10)2 will give us the same solution, which is 100. So, both values are valid solutions when solving the equation x2 = 100.

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Problem 3

Simplify (3x)2, x = 2.

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36

Explanation

 (3x)2 = 9x2
9x2 = 9(2)2 = 9 × 4 = 36

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Problem 4

A square has a side length x = 7cm. What is its area?

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49cm2

Explanation

Area of square = x2,
Here, x = 7, so Area of square = 72 = 49cm2
 

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Problem 5

An object is moving at a speed x = 5 m/s, and its kinetic energy is proportional to the square of its speed. Find the value of kinetic energy.

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25

Explanation

Kinetic energy = x2
X = 5, so x2 = 52 = 25
 

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FAQs on X Squared

1.Is x2 always positive?

No, x2 is always non-negative, not always positive. Even if x is negative, squaring it gives a positive result. But if x = 0, then x2 = 0. 

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2. What is the square root of x2?

The square root of x2  is the absolute value of x. So √x2 = x.
 

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3.Why is x2 important?

x2 is important in algebra, geometry, physics, and engineering. It helps model areas, physical motion, and quadratic relationships.
 

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4.Why is it called x squared?

The term ‘squared’ originates from geometry, where the area of a square is calculated as side  side = x2. So, ‘squared’ means raising a number to the power of 2. 

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5. Is 1 a perfect square?

Yes, 12 = 1 × 1 = 1, so 1 is a perfect square.
 

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Jaskaran Singh Saluja

About the Author

Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

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Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.

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