Question 56519
8.3 #  28
Solve by substitution
Mcgraw Hill 6th editon,
:
L1) 4x-12y=5
L2) -x+3y=  -1
: Solve L2) for x and substitute it in for the x in L1) and solve for y:
-x+3y-3y=-1-3y
-x=-1-3y
-1(-x)=-1(-1-3y)
L1) {{{x=highlight(1+3y)}}}
L2) {{{4*highlight(1+3y)-12y=5}}}
{{{4(1)+4(3y)-12y=5}}}
{{{4+12y-12y=5}}}
{{{4=5}}}
Your y was eliminated and 4 does not = 5, therefore there is no solution.  Graphically, these line are parallel and never intersect.  We call these equations inconsistent.
Happy Calculating!!!