SOLUTION: Solve the following system of equations by using the inverse of the coefficent Matrix (AX=B) x+3y=-9 5x+8y=-31 i also need the ordered pair solution

Algebra ->  Matrices-and-determiminant -> SOLUTION: Solve the following system of equations by using the inverse of the coefficent Matrix (AX=B) x+3y=-9 5x+8y=-31 i also need the ordered pair solution      Log On


   

Question 632917: Solve the following system of equations by using the inverse of the coefficent Matrix (AX=B) x+3y=-9 5x+8y=-31 i also need the ordered pair solution
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

Note: Post each question separately, not necessary to use pictures,

just list Eqs with the following instructions:

Solve the system of equations by using the inverse of the coefficient matrix.

 x+3y = -9 

5x+8y = -31                             

A+=%28+matrix%282%2C2%2C1%2C3%2C5%2C8%29%29 = -7  

adjA+=+%28matrix%282%2C2%2C8%2C-3%2C-5%2C1%29%29  Note: How the above numbers flipped and the 2 minuses

A%5E%28-1%29 = (1/-7)+%28matrix%282%2C2%2C8%2C-3%2C-5%2C1%29%29+



A%5E%28-1%29+=++%28matrix%282%2C2%2C-8%2F7%2C3%2F7%2C5%2F7%2C-1%2F7%29%29+

and...



Ordered pair (-3,-2) the solution for this system of equations

Checking our answer using the Elimination Method:

x+3y= -9 

5x+8y= -31  |multiplying 1st EQ by 5 and Subtracting  from the 2nd EQ

 -7y = 14

  y = -2   and x = -3  as -3+%2B+3%2A%28-2%29+=+-9

(x,y) Ordered pair (-3,-2) the solution for this system of equations