) solve by substitution

Question

2a-3b+2c=1  

4a+b-3c=23

c=-4     (3,-1,-4)

Answer 1

Substitute the value of c into the first two equations.  The first two equations will then be in terms of a and b.  From there, you can substitute the value b in the first equation.  The first equation will be in terms of only a, and you will only have one equation to solve.  After you found a, substite the value of a into the second equation to find b.

 

Here is how you find a.

 

 

Substitute    c=-4  to get .

 

2a - 3b = 9                eq1

4a + b = 11                eq2

 

Substituting b for a,

 

2a - 3(11 - 4a) = 9

2a - 33 + 12a = 9

14a - 33 = 9

14a = 42

   a = 3

 

 

Go find b now.