Question 174464
SUBSTIUTION: USE WHEN ONE EQUATION HAS NO INTEGER.
Y=3X
2Y-8=2X
2*3X-8=2X
6X-8-2X=0
4X=8
X=8/4
X=2 ANS.
Y=3*2
Y=6 ANS.
PROOF:
2*6-8=2*4
12-8=4
4=4
-----------------------------
ADDITION: USE WHEN ONE UNKNOWN IS A MULTIPLE OF THE SAME UNKNOWN IN THE OTHER EQUATION.
Y-3X=0 MULTIPLY THIS EQUATION BY -2 & ADD
2Y-2X=8
-2Y+6X=0
2Y-2X=8
----------
4X=8
X=8/4
X=2
Y-3*2=0
Y-6=0
Y=6
----------------
CROSS MULTIPLICATION: USE WHEN THERE ARE FRACTIONS INVOLVED.
Y/4X=3/4
4Y=12X
Y=12X/4
--------
3Y/3X=3
3(12X/4)/3X=3
(36X/4)/3X=3
36X/4=9X
36X=36X