SUBSTITUTION METHOD: Pair of linear equation in two variables

INTRODUCTION:-

Pair of the linear equation means we have two equations with the degree of the polynomial one & each equation has two variables.

In this blog, we will discuss how to find the values of variables in the pair of linear equation by the substitution method.

In the substitution method, we find the values of variables by putting the values.


Substitution Method:-

In this method, we find the values of both variables by finding the value of any one variable from any equation & then put it in other equation.

Take a question for better understanding...

Question

Solve the pair of linear equation in two variables-
x+5y=12
4x-3y=9

Answer

Here we have two equations-
x+5y=12  --------Eq. 1
4x-3y=9  ---------Eq. 2

From Eq. 1 we will find the value of x

x+5y=12
x=12-5y  ---------Eq. 3

Now put the value of x (Eq. 3) in Eq. 2 to get value of  y.

4x-3y=9
4(12-5y)-3y=9
48-20y-3y=9
48-23y=9
-23y=9-48
-23y=-39
y=(-39)÷(-23)
y=39/23  ---------Eq. 4

Put the value of y (Eq. 4) in Eq. 1 to get the value of variable x.

x+5y=12
x+5(39÷23)=12
x+(195÷23)=12
x=12-(195÷23)
x={(12×23)-195}÷23
x={276-195}÷23
x=81÷23
x=81/23  --------Eq. 5

We have values of x=81/23 & y=39/23.

CONCLUSION:-

So here we get values of both variables x & y by Substitution method. In the next blog, we will find the values of a variable by the elimination method.