Here we will discuss about equations. An open sentence containing the sign ‘=‘ is called an equation.

Let’s recall how to solve numerical expressions, i.e., 11 + 7 - 3 and algebraic expressions, i.e., 5x - 2 + 10x/2

We already know that the statement 3 + 5 = 8 is true but the statement 7 + 2 = 8 is not true or 2 + 3 < 5 is also not true.

Such mathematical statements which may either be true or false but not both are called mathematical sentences.

The statement 2 + x = 5 may be true or false depending on the value of x.

If x = 1 then 2 + 1 = 5 is false. If x = 3 then 2 + 3 = 5 is true.

Thus, we can say that the mathematical sentence containing the variable becomes either true or false depending upon the value of the variable.

This type of sentence is called an open sentence, thus 2 + x = 5 is an open sentence.

A statement of equality of two algebraic expressions which involves one or more literals (variables) is called an equation.

3 + x = 7 is an equation.

The set of values of variables which makes the open sentence true is called the solution set.

**Note:**

Every equation has two sides — L.H.S. (left-hand side) and R.H.S. (right-hand side).

Literals involved in the equation are called variables. These are usually denoted by letters of English alphabet.

An equation may contain any number of variables.

**For example:**

(i) 5x + 7 = 19 (ii) 2x + 13y = 8 (iii) 5x - 3y + 4z - 14 = 0

**Find the solution set for the following open sentences. **

(a) x + 4 = 7

(b) x - 3 > 5

(c) x/2 < 10

The solution set for the following open sentences are explained below step-by-step.

**(a) x + 4 = 7**

**Solution:**

x + 4 = 7

If x = 0, then 0 + 4 ≠ 7

If x= 1, then 1 + 4 ≠ 7

If x = 2, then 2 + 4 ≠ 7

If x = 3, then 3 + 4 = 7

Therefore, the solution set for the open sentence x + 4 = 7 is 3.

**(b) x - 3 > 5**

**Solution:**

x - 3 > 5

If x = 6, then 6 - 3 ≯ 5

If x = 8, then 8 - 3 ≯ 5

If x = 9, then 9 - 3 = 6 > 5

If x = 10, then 10 - 3 > 5

If x = 11, then 11 - 3 > 5

Therefore, the solution set for the open sentence x - 3 > 5 are all the values of the variable greater than 8, i.e., 9, 10, 11, 12...

**(c) x/2 < 10**

**Solution:**

x/2 < 10

If x = 24, then 24/2 ≮ 10

If x = 20, then 20/2 ≮ 10

If x = If x = 19/2, then < 10

If x = 16 then 16/2 < 10

Therefore, the solution of the variable less than 20, i.e., 19, 18, 17, 16, 15, 14, ....

● **Equations**

**How to Solve Linear Equations?**

**Problems on Linear Equations in One Variable**

**Word Problems on Linear Equations in One Variable**

**Practice Test on Linear Equations**

**Practice Test on Word Problems on Linear Equations**

● **Equations - Worksheets**

**Worksheet on Word Problems on Linear Equation**

**7th Grade Math Problems****8th Grade Math Practice**** **

**Didn't find what you were looking for? Or want to know more information
about Math Only Math.
Use this Google Search to find what you need.**

## New! Comments

Have your say about what you just read! Leave me a comment in the box below. Ask a Question or Answer a Question.