SOLUTION: use substitution to solve 2x + 3y = 9 5x

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Question 66042This question is from textbook an incremental development
: use substitution to solve
2x + 3y = 9
5x - 2y = -25 This question is from textbook an incremental development

Found 2 solutions by checkley71, praseenakos@yahoo.com:
Answer by checkley71(8403) (Show Source):
You can put this solution on YOUR website!
2X+3Y=9 NOW MULTIPLY THIS EQUATION BY 2 &
5X-2Y=-25 NOW MULTIPLY THIS EQUATION BY 3 WE CAN NOW ADD THESE 2 EQUATIONS THUS
4X+6Y=18
15X-6Y=-75 NOW ADD
-----------------------
19X=-57
X=-57/19
X=-3 SOLUTION.
NOW REPLACE X BY -3 AND SOLVE FOR Y THUS
2*-3+3Y=9
-6+3Y=9
3Y=9+6
3Y=15
Y=15/3
Y=5

Answer by praseenakos@yahoo.com(507) (Show Source):
You can put this solution on YOUR website!
QUESTION:

use substitution to solve
2x + 3y = 9
5x - 2y = -25

ANSWER:

2x + 3y = 9 --------------(1)

5x - 2y = -25-------------(2)
Solve either one of the equations for one of the unknown variables by isolating that variable on one side of the equal sign....then the other unknown variable will be presebt on the other side of the equal sign.

So (1)==> 2x = 9 - 3y

==> x = ( 1/2)( 9 - 3y)

==> -19y = -95

substitute this value of x in equation (2)

==> 5(9/2 -3y/2) - 2y = -25

==> 45/2 - 15y/2 - 2y = -25

Multi ply both sides by 2

==> 2*45/2 - 2*15y/2 - 2*2y = 2*-25

==> 45 - 15y - 4y = -50

==> 45 - 19 y = -50

Subtract 45 from both sides...

==> 45 - 19y - 45 = -50- 45

==> -19y = -95

Divide both sides by -19

==> -19y/-19 = -95/-19

==> y = 5

So we got value of y = 5

Now substitute this value of y in ....x = ( 1/2)( 9 - 3y)

==> x = ( 1/2)( 9 - 3*5)

==> x = ( 1/2)( 9 - 15)

==>x = ( 1/2)(-6)

==> x = (1* -6)/2

==> x = -6/2

==> x = -3

So the solution is x = -3 and y = 5

You can check your answer by plugging these values in the given pair of equations....

Hope you understood

Regards.

praseena.

SOLUTION: use substitution to solve 2x + 3y = 9 5x - 2y = -25