Simple Equations

Simple Equations

For Grade 7

Basic points to remember

• A variable is a letter used in an equation. For example in 30x+10, x is the VARIABLE

• If any number and a variable are written together, it means multiply the number and the variable. For Example in 30a+10=y, Y is a normal variable and 30x means 30 multiplied with a or 30 $\times$ a

• Any equation can have more than one variable but not more than one answer.

What is the difference between an equation and an expression ?

• An expression is a equation without any particular value of a variable and doesn't have any equal to symbol due to which it can't be solved. Example is 3a+30

• There are two types of expressions which will be shown in the next slide.

• An equation is a statement that the values of two mathematical expressions are equal (indicated by the sign =). Example is 3a+30=60

Types of Expressions

• The first type of expression is NUMERICAL EXPRESSIONS

• These expressions only consist of numbers. For example 3+7-1

• The second type is ALGEBRAIC EXPRESSIONS

• This type of expressions consist of numbers and variables. For example 4a-10

• Now, solve some questions

Multiple Choice

Which of these defines an expression?

• Any letter or a word is an expression

• A group of words and numbers forms an expression

• An expression is a mix of any two equations

• An expression is a equation without any particular value of a variable

Multiple Choice

Which if these defines an equation?

• An equation is the second type of expression

• It is the radius of a circle

• It is a type of variable

• It is a statement that the values of two mathematical expressions are equal (indicated by the sign =)

Multiple Select

Identify the algebraic expression/s from the following

• 10+3+a

• 3a+19

• 3+10-10

• 20-20

• 72-100+289

Multiple Select

Find the variable/s in 10x+30a=12b

• a

• 30

• 10

• b

• x

How to solve an equation by the transposing method ?

• 3x+10=100(leave the number with the variable and bring the other number to the other side or we can say TRANSPOSE with making its symbol from + to -. 

• 3x=100-10(Find the solution of 100-10)

• 3x=90(Now, 3x means 3 multiplied by x, so we will transpose 3 and make the symbol from  $\times$  to  $\div$ symbol.

• x=90 $\div$  3(Solve 90 $\div$ 3

• x=30(The final value of x is 30)

•  $\therefore$  The value of x is 30

Multiple Choice

The value of 'a' in 3a=30 is

• 30

• 3

• 10

• -3

Multiple Choice

Which of these shows the correct value of 'z' in the equation: 10z+10=80

• 7

• 70

• 10

• 0

• 80