so we convert them to slope-intercept form which is y=mx+b where m=slope and b=y intercept
first line (-1,-2) (1,2) slope=(y1-y2)/(x1-x2) x1=-1 y1=-2 x2=1 y2=2 subsitute (-2-2)/(-1-1)=-4/-2=4/2=2 slope=2 subsitute y=2x+b subsitute another point (1,2) x=1 y=2 is one solution 2=2(1)+b 2=2+b subtract 2 from both sides 0=b the equation is y=2x+0 or y=2x
other equation (-2,10) (4,1) x1=-2 y1=10 x2=4 y2=1 subsitute (10-1)/(-2-4)=9/-6=-3/2 slope=-3/2 y=-3/2x+b subisute points that work (-2,10) x=-2 10=y is one solution 10=-3/2(-2)+b 10=6/2+b 10=3+b subtract 3 7=b y=-3/2x+7
we have y=-3/2x+7 and y=2x subsitute 2x=y=-3/2x+7 2x=-3/2x+7 add 3/2x to both sides 2x+3/2x=7 2x=4/2x 4/2x+3/2x=7 7/2x=7 multiply both sides by 2/7 x=14/7 x=2 subisute for y y=2x y=2(2) y=4
