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 Quadratic Expressions and Equations

In this article, we will understand the importance of quadratic expressions and equations and discuss their differences and formulae.

A quadratic expression has a variable with the largest power of 2. The word quadratic is derived from ‘quad’, which means ‘square.’ The expression should have a power of 2 and not higher or lower. A quadratic expression graphically shows the route taken by a parabola and can aid in various practical calculations such as determining the height and flight time of a rocket.

Equations with quadratic expressions

Quadratic equations are second-degree algebraic formulae with the expression ax2 + bx + c = 0. A quadratic equation is often known as a ‘degree 2 equation.’ A quadratic equation is used in many contexts. Were you aware that when a rocket is fired, its path is determined by a quadratic equation? A quadratic equation is also useful in physics, engineering, and astronomy.

The quadratic equations have two solutions and are second-degree equations in x. These two answers for x are the quadratic equations’ roots and are denoted as α and β.

Standard quadratic equation samples

Starting with the standard form is the simplest way to learn quadratic equations. While not every quadratic equation you encounter will be in this format, working on these examples is still beneficial. Remember that the first constant, a, cannot be zero.

Examples of quadratic equations in standard form (ax2 + bx + c = 0) include:

6x² + 11x – 35 = 0

2x² – 4x – 2 = 0

-4x² – 7x +12 = 0

20x² -15x – 10 = 0

x² -x – 3 = 0

5x² – 2x – 9 = 0

3x² + 4x + 2 = 0

-x² +6x + 18 = 0

Formulae for quadratic expressions

We can solve a quadratic expression if we transform it into a quadratic equation by equalising it to zero. The zeros of the equation are the values of the variable x that fulfil the quadratic expression and equalise it to zero. 

Some expressions are difficult to solve using the factorising approach. Here lies the importance of the quadratic formula. The quadratic formula is frequently referred to as the ‘Quadranator.’ The quadrotor is sufficient to solve any quadratic expression issues. The formula for quadratic expressions is as follows.

Expression = ax2+bx+c

x=-b b2-4ac2a

How to distinguish expressions from equations?

Algebraic expressions contain numbers, variables, or a mix of the two. As you can see in the following formulas, one ingredient is missing from the equations. Can you guess what that is?

x –  2

7x + 8

15 – 6x

The above mathematical equations are missing an equal symbol! This is what distinguishes writing expressions from writing equations.

Variables, coefficients, whole integers, decimals, exponents, addition, subtraction, multiplication, and division are possible in equations and expressions. But, algebraic equations always contain an equal sign.

3x – 1 = x + 4

x – 7 = 3 – 5x

6 + 2x = 8x + 1

Each above equation has two sides: a right and a left side. An equation is made up of two expressions in theory. The equal sign signifies that the equation’s two sides are equivalent expressions.

To sum it up, a numerical expression is a set of numbers and variables that do not have an equal sign. An equation is a set of numbers and variables that contains an equal sign.

Differences between expression and equation:

The differences between expressions and equations can be summarised in the following points.

  • A mathematical expression is a statement that combines numbers, variables, and operators to indicate the value of something. 
  • A mathematical statement with two expressions made equal is defined as an equation.
  • An expression is a sentence fragment that represents a single number value. A statement that proves the equivalence of two expressions, on the other hand, is referred to as an equation.
  • The equation is optimised by evaluating it and substituting values for variables. An equation, on the other hand, is solved.
  • An equal symbol (=) denotes an equation. An expression, on the other hand, lacks a relation sign.
  • An equation is a double expression with an equal sign separating the left and right sides. In contrast to an expression, which is one-sided, there is no delineation such as left or right side.
  • An expression’s response can be either an expression or a numerical value. In contrast, an equation can only be true or false.


As a result of the preceding explanation, it is clear that these two mathematical structures differ significantly. An expression does not indicate a relationship, but an equation does. Because an equation has an ‘equal to’ sign, it reflects the solution or value of the variable. However, because an expression lacks an equal sign, there is no clear response, and the variable’s value cannot be presented.


Frequently asked questions

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