Question

substitution method in chapter linear equation

Answer 1

Let us  take an example of this method :~


(a) x + y = 14 and x – y = 4

 sol.   Let us use the first equation to express one variable in terms of another variable;

x + y = 14

Or, x = 14 – y

Substituting the value of x in second equation we get;

x – y = 4

Or, 14 – y – y = 4

Or, 14 – 2y = 4

Or, 2y = 14 – 4 = 10

Or, y = 5

Substituting the value of y in first equation, we get;

x = 14 – y

Or, x = 14 – 5 = 9

Hence, x = 9 and y = 5

hope u will understand...

Answer 2

It is one of the most commonly used methods in Linear equation.

Procedure:-
1.Solve one of the given equations for one of the variables,whichever is convenient.
2.Substitute the value of the variable in the other equation.
3.Solve the resulting single variable equation and substitute this value into either of the 2 original equations and solve it to find the value of second variable.

Example:-
x + y = 20 .......... (1)
x – y = 10 ............ (2)

 We can write the first equation as

 x = 20 – y ............(3)

Substituting the value of x in second equation we get;

x – y = 10

=> 20 – y – y = 10

=> 20 – 2y = 10

=> 2y = 20 – 10 = 10

=> y = 5

Substituting the value of y in first equation, we get;

x = 20 – y

=> x = 20 – 5 = 15

Hence, x = 9 and y = 5

Hope it helps you!!!