Question

Which is the value of Dx from the following equation x+2y=-1; 2x-3y=12​

Answer 1

Answer:

Given, x + 2y = -1 => x + 2y + 1 = 0

2x - 3y = 12 => 2x - 3y - 12 = 0

according to Cramer's rule,

when two equations a₁x + b₁y + c₁ = 0 and a₂x + b₂y + c₂ = 0 .

now, use it here,

equations :- x + 2y + 1 = 0

2x -3y - 12 = 0

x/{2 × (-12) - 1 × (-3)} = -y/{1 × (-12) - 1 × 2} = 1/{1 × (-3) - 2 × 2}

=> x/(-24 + 3) = -y/(-12 - 2) = 1/(-3 - 4)

=> x/-21 = -y/-14 = 1/-7

=> x = -21/-7 = 3 and y = 14/-7 = -2

hence, x = 3 and y = -2

Answer 2

Answer:

x+2y = -1 ---(1)

2x-3y= 12 ---(2)

(1)×2-(2)

2x+4y= -2

2x-3y= 12

- + -

7y = -14

y= -14/7

y= -2

substitute the value of y in (1)

x+2(-2)= -1

x-4= -1

x= -1+4

x= 3