How do solve the following linear system?: x-4y=2 , 2x+6y=5 ?

1 Answer
Feb 17, 2016

(16/7, 1/14)

Explanation:

In order to solve systems of linear equations, you can either use the

  1. Elimination Method
  2. Substitution Method
  3. Graphing

In this case, I would use the elimination method but note that you may use any method that you are comfortable with and still arrive at the same answer.

[Solution]
x - 4y = 2
2x + 6y = 5

Multiply 2 to both sides of the first equation...

2x - 8y = 4

Doing this makes the coefficient of x in the two equations the same. This enables us to subtract one equation from the other to eliminate the x variable

[Subtracting one equation from the other]
2x + 6y = 5
2x - 8y = 4

14y = 1
y = 1/14

Now that we know the value of y, we can now evaluate any of the two equations with the value of y to get the value of x

x - 4(1/14) = 2
x - 2/7 = 2
x = 2 + 2/7
x = 16/7

[Checking]
Substituting to equation 1 -> x - 4y = 2
16/7 - 4(1/14) = 2
16/7 - 2/7 = 2
14/7 = 2
2 = 2

Substituting to equation 2 -> 2x + 6y = 5
2(16/7) + 6(1/14) = 5
32/7 + 3/7 = 5
35/7 = 5
5 = 5

[Final Answer]
(16/7, 1/14)