How do you solve the following linear system 2x-y=4, x+3y=1? ?

1 Answer
Jun 22, 2018

Solve for one term with respect to another, then solve for the second term, then back-solve for the first. You will find that x=13/7 and y=-2/7

Explanation:

First, we'll want to solve for either x in terms of y or vice versa. For the sake of argument, we'll sove for x in terms of y using the second expression:

x+3y=1

rArrcolor(blue)(x=1-3y)

Now, we take that solution for x and substitute it in, in expression 1:

2color(blue)(x)-y=4

2color(blue)((1-3y))-y=4

2-6y-y=4

2-7y=4

-7y=2

color(green)(y=-2/7)

We now have a solution for y. We can then plug it into either expression to solve for x:

x+3color(green)(y)=1

x+3color(green)((-2/7))=1

x-6/7=1

x=1+6/7

color(green)(x=13/7)

And now we have our solution:

x=13/7, y=-2/7