Question

solve by elimination method. 3x-y=7, 2x+5y=-1​

Answer 1

Answer:

h 45 h h k 6 ke sath hi yah kaha ja

Answer 2

$\large\underline{\sf{Solution-}}$

Given pair of linear equations are

$\rm :\longmapsto\:3x - y = 7 - - - (1)$

and

$\rm :\longmapsto\:2x + 5 y = - \: 1 - - - (2)$

On multiply equation (1) by 2 and equation (2) by 3, we get

$\rm :\longmapsto\:6x -2 y = 14 - - - (3)$

and

$\rm :\longmapsto\:6x + 15 y = - \: 3 - - - (4)$

On Subtracting, equation (4) from equation (3), we get

$\rm :\longmapsto\: - 17y = 17$

$\bf\implies \:\boxed{ \tt{ \: \: y \: = \: - \: 1 \: \: }}$

On substituting y = - 1 in equation (1), we get

$\rm :\longmapsto\:3x - ( - 1) = 7$

$\rm :\longmapsto\:3x + 1= 7$

$\rm :\longmapsto\:3x = 7 - 1$

$\rm :\longmapsto\:3x = 6$

$\bf\implies \:\boxed{ \tt{ \: \: x \: = \: \: 2 \: \: }}$

So, Solution of pair of linear equations is

$\red{\begin{gathered}\begin{gathered}\bf\: \rm :\longmapsto\:\begin{cases} &\sf{x \: = \: 2} \\ &\sf{y \: = \: - \: 1} \end{cases}\end{gathered}\end{gathered}}$

Verification :-

Consider,

$\rm :\longmapsto\:3x - y = 7$

On substituting the values of x and y, we get

$\rm :\longmapsto\:3(2) - ( - 1) = 7$

$\rm :\longmapsto\:6 + 1 = 7$

$\rm :\longmapsto\:7 = 7$

Hence, Verified

Consider

$\rm :\longmapsto\:2x + 5 y = - \: 1$

On substituting the values of x and y, we get

$\rm :\longmapsto\:2(2)+ 5 ( - 1) = - \: 1$

$\rm :\longmapsto\:4 - 5 = - \: 1$

$\rm :\longmapsto\: \: - \: 1 \: = - \: 1$

Hence, Verified