Solve the system by substitution.
2x+y=-11
3x-4y=11

a:(3,5)
b:(-5,-3)
c:(-3,-5)
d:(5,3)

Question

Solve the system by substitution.
2x+y=-11
3x-4y=11

a:(3,5)
b:(-5,-3)
c:(-3,-5)
d:(5,3)

anonymous · Answer

Solve for x on the first equation.

Then *substitute* that value into the second equation.

anonymous · Answer

What do you get when you solve for x on the first equation?

anonymous · Answer

x=-y/2-11/2

anonymous · Answer

@muntoo

anonymous · Answer

Now plug the value of x you just got into the second equation, 3x-4y=11.

anonymous · Answer

After I plugged it in and solved for y I got -3 @muntoo

anonymous · Answer

$$\large{       3x - 4y = 11       \ \ \
3({-y\over 2}-{11\over 2}) - 4y = 11        \ \ \\
3({-y-11\over 2}) - 4y = 11        \ \ \
3(-y-11) - 8y = 22              \
-3y-33 - 8y = 22               \
-11y = 55         \
y = -5        }$$

Now plug that value of y back into one of the equations (any one) to find x.