Question

Solve the equations $3x–y=5,x+3y=5$

• A. 1, 2
• B. 2, 1
• C. -1, -1
• D. -2, -2

Answer 1

The correct option is B

2, 1

Given equations

3x – y = 5...........(i)

x + 3y = 5........(ii)

Since the coefficient of x in (i) is equal to coefficient of y in (ii) and the coefficient of y in (i) is equal to coefficient of x in (ii)

Adding (i) and (ii)

4x + 2y = 10 $\Rightarrow$ 2x + y = 5......(iii)

Subtracting (i) and (ii) we get

2x - 4y = 0 $\Rightarrow$ x - 2y = 0 or x = 2y........(iv)

Substituting (iv) in (iii) we get

5y = 5 or y = 1

$\Rightarrow$ x = 2 (from iv)