Question

9. What is the solution to 4x - y = 8, 6x + y = 2

Answer 1

Answer:

x = 1

y = -4

Step-by-step explanation:

You can use 2 methods to solve this, substitution or elimination.

Elimination:

You want to try and get rid of one variable in the pair of equations.

We add them together since y and -y cancel each other out when added.

Now, we have a much simpler equation.

   4x - y = 8

+  6x + y = 2

------------------

  10x  = 10

      x =  1

Now, you can just plug it back in to one of the equations to get y.

(4 x 1) - y = 8

4 - y = 8

y = -4

Substitution:

You can also try and change the equation so that there is only one variable by setting the other equation equal to a variable.

This one is easier to do:

6x + y = 2

y = -6x + 2

Now, plug it into the first equation replacing y, since they are equal, and solve:

4x - y = 8

4x - (-6x + 2) = 8

4x + 6x - 2 = 8

10x = 10

x = 1

Now, you can just plug it back in to one of the equations to get y.

6x + y = 2

(6 x 1) + y = 2

6 + y = 2

y = -4

:)