Question

x + 5 = 3y, 4x + y = 2​

Answer 1

Your system of equations looks like this

{

4

x

−

y

=

−

5

−

2

x

+

3

y

=

10

Multiply the second equation by

2

to get

{

4

x

−

y

=

−

5

−

4

x

+

6

y

=

20

Notice that if you add the left-hand side of the equations and the right-hand sides of the equations separately, you can eliminate the

x

-term.

This will allow you to find the value of

y

, since you'll be left with one equation with one unknown,

y

.

{

4

x

−

y

=

−

5

−

4

x

+

6

y

=

20

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

4

x

−

y

−

4

x

+

6

y

=

−

5

+

20

5

y

=

15

⇒

y

=

3

Now take the value of

y

into one of the two original equations to solve for

x

4

x

−

3

=

−

5

4

x

=

−

2

⇒

x

=

−

1

2