Question 83179
X+Y=-1, Y=-X-1 (RED LINE)
2X-Y=7, -Y=-2X+7, Y=2X-7 (GREEN LINE)
NOW SOLVE THESE 2 EQUATIONS BY SUBSTITUTING (-X-1) FOR Y IN THE SECOND EQUATION & SOLVE FOR X
2X-(-X-1)=7
2X+X+1=7
3X=7-1
3X=6
X=6/3
X=2 ANSWER.
2+Y=-1
Y=-1-2
Y=-3 ANSWER.
{{{ graph( 300, 200, -6, 5, -10, 10, y = -x -1, y = 2x -7) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = -x -1 and y = 2x -7).