Multiply first equation with -2
- 4 x + 12 y = -6
Note that, if you add down, the y's will cancel out.
- 4 x + 12 y = - 6
4 x + 9 y = - 1
( - 4 x + 4 x ) + ( 12 y + 9 y ) = -6 + ( -1 )
0 + 21 y = -6 - 1
21 y = - 7 Diwide both sides with 21
y = - 7 / 21
( Remark: 7 / 21 = 1 / 3 )
y= - 1 / 3
First equation:
2 x - 6 y = 3
2 x - 6 * ( - 1 / 3 ) = 3
2 x + 6 / 3 = 3
2 x + 2 = 3
2 x = 3 - 2
2 x = 1 Divide both sides with 2
x = 1 / 2
x = 1 / 2 , y= - 1 / 3
solve equations by elimination
2x-6y=3 (1)
4x+9y=-1 (2)
2 answers
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