10th Class Mathematics Pair of Linear Equations in Two Variables Question Bank MCQs - Pair of Linear Equations in Two Variables

If \[x=a,\] \[y=b\] is the solution of the pair of equation \[\text{x}-\text{y}=\text{l}\]and \[\text{x}+\text{y}=\text{4},\]then the respective values of a and b are: (CBSE 2012)

A) 3, 5

B) 5, 3

C) 3, 1

D) -1, -3

Correct Answer: C

Solution :

[c] The given equations are

\[x-y=2\] ...(1)

\[x+y=4\] ...(2)

On adding eqs, (1) and (2), we get

\[2x=6\,\,\,\,\,\,\,\,\,\,\,\,\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,x=3\] ...(3)

\[\therefore \,\,\,\,\,\,\,\,\,\,\,\,y=1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\Rightarrow \,\,\,\,\,\,\,\,a=3,\,b=1\]