Question 219612
y=x+7 (red line)
y=-x+2 (green line)
These two equations are perpendicular because their slopes are negative recipricals of each other. (1 & -1)
{{{ graph( 300, 300, -10, 10, -10, 10, x +7, -x +2 ) }}} (graph 300x300 pixels, x from -10 to 10, y from -10 to 10, of TWO functions x +7 and -x +2).