SIMULTANEOUS EQUATIONS
3X+4Y=5
2X-3Y=9

Question

SIMULTANEOUS EQUATIONS
3X+4Y=5
2X-3Y=9

solomonzelman · Answer

3X+4Y=5    ---->  times 2 --->   6X+8Y=10  
2X-3Y=9    ---->  times 3 --->   6x-9Y=27              (subtract 2nd equation, from the 1st)
                                                      ----------
                                                      0X +17y=-17
17y=-17 ---->    y=-1

2X-3Y=9   substitute   -1  for  y
2X-3(-1)=9
2X+3=9
subtract 3 from both sides
2X+3-3=9-3
2X=6
divide both sides by 2
X=3

So we get X=3 & Y=-1

Lets check.

3X+4Y=5
2X-3Y=9

3(3)+4(-1)=5     ---->   9-4=5   --->   5=5
2(3)-3(-1)=9    ---->    6-(-3)=9  --->   6+3=9 ----> 9=9

YES, CORRECT!!!!
X=3    AND    Y= -1

solomonzelman · Answer

tnx for the medal!