Question

M not understanding substitution method class 10 ... can anyone hlp me?

Answer 1

Substitution method for solving a pair of linear equations:

Consider the equations: 2x + 3y = 9 and x – y = 3

For solving simultaneous equations,

Let, 2x + 3y = 9……..(1) and x – y = 3 ……..(2)

From Equation (2) we get, y = x – 3……………(3)

Now, as we understood above that in the substitution method, we find the value of one variable in terms of other and then substitute back.

Now, we know that y = x – 3

Substituting the value of y in equation (1), we get

2x + 3y = 9

⇒ 2x + 3(x – 3) = 9

⇒ 2x + 3x – 9 = 9

⇒ 5x = 18

⇒ x = 185

Now, the value of y can be found out using equation (3)

So, y = x – 3

⇒ y = 185  – 3

⇒ y = 35

Hence the solution of simultaneous equation will be: x = 185  and y = 35

In this way, we can find out the value of the unknowns x and y using substitution method.