How do you solve the system -3(5+x)=y3(5+x)=y and 5(x-3)=2y+45(x3)=2y+4?

1 Answer
Jun 9, 2015

The solution for the system of equations is:
color(blue)( x = -1 , y =-12 x=1,y=12

Explanation:

-3(5+x)=y3(5+x)=y
-15 -3x = y153x=y
y +3x = -15y+3x=15 ............equation (1)(1)

5x-15=2y+45x15=2y+4
5x - 2y = 4 +155x2y=4+15
5x - color(blue)(2y) = 195x2y=19................equation (2)(2)

  • Multiplying equation (1)(1) by 22
    y +3x = -15y+3x=15
    color(blue)( 2y)+6x = -302y+6x=30 ...........equation (3)(3)
  • Adding equations 2 and 32and3 to eliminate color(blue)(2y)2y

5x - cancelcolor(blue)(2y) = 19
cancelcolor(blue)( 2y)+6x = -30
11x = -11
color(blue)(x = -1

Substituting x in equation (1) to find y:
y = -15-3x
y = -15-3.(-1)
color(blue)(y = -12