x-2y=5 -3x+2y=7

Question

How do I solve x-2y=5 -3+2y=7 using Gauss- Jordan elimination ?

Answer 1

x - 2y = 5             eq1

-3x + 2y = 7         eq2

 

 

We can use the substitution method.

 

Substitute eq1 into eq2, so that we have only one equation with one variable to work with.  Let's get eq2 in terms of y.

 

 

-3(5 + 2y) + 2y = 7

 

 

Now solve for y from this equation.

 

-15 - 6y + 2y = 7

      -4y - 15 = 7

      -4y = 22

         y = -22/4

         y = -11/2

 

Now, substitute this value of y into eq1 to solve for x.

 

x = 5 + 2y

x = 5 + 2(-11/2)

x = 5 - 11

x = -6

 

 

The solutions are

 

x = -6

y = -11/2

 

We can put y in decimal form.

 

y = 5.5