use addition method
2007-11-03 19:34:50 · 3 answers · asked by Mary L 2 in Science & Mathematics ➔ Mathematics
-7x + 3y = - 42
9x - 2y = - 6
-14x + 6y = - 84
27x - 6y = - 18--------ADD
13x = - 102
x = - 102 / 13
714/13 + 3y = - 42
3y = -546/13 - 714/13
3y = 1260/13
y = 420 / 13
x = - 102 / 13 , y = 420 / 13
( "Unfriendly" numbers for a solution?!!)
2007-11-03 21:25:59 · answer #1 · answered by Como 7 · 1⤊ 1⤋
-7x+3Y=-42 => (7x-42)/3=Y
9x=2y-6 => (9x+6)/2=y
Y=Y => (7x-42)/3=(9x+6)/2
14x-84=27x+18
-102=13x
x= -102/13
y=14*(-102/13) -84
2007-11-03 21:16:10 · answer #2 · answered by Anonymous · 0⤊ 0⤋
-7x + 3y = -42
9x - 2y = -6
multiply the top one by -2 and the bottom one by -3
14x - 6y = 84
-27x +6y = 18
now add the equations together
-13x=102
x= -102/13
If you substitute that in for x in one of the original equations you will get the value for y
2007-11-03 19:44:54 · answer #3 · answered by cgflann 4 · 1⤊ 1⤋