Question

Show that the system has no solution.
x + 2y = -4
y = -1/2x - 4

Answer 1

change x+2y=-4 so x is alone

x+2y=-4

x+2y-2y=-4-2y

x=-4-2y

substitute -4-2y into x in y=-1/2x-4

y=-1/2(-4-2y)-4

multiply 1/2 with everything inside the parentheses

y=-1/2(-4)-1/2(-2y)-4

y=2+1y-4

simplify

y=1y-2

remove 1y on both sides

y-y=1y-y-2

0=-2

no solution