using the addition (elimination) method. If the answer is a unique solution present it as an ordered pair (x,y) if not specify wether the answer is "no solution" or "infinitely many solutions"
5x+y=-2
4x+7y=2
2007-02-24 10:38:08 · 3 answers · asked by chickiejam 1 in Science & Mathematics ➔ Mathematics
5x + y = -2 Write down the given
4x + 7y = 2
-7(5x + y = -2) multiply the 1st equation with -7 so that y's
4x + 7y = 2 will cancel
-35x - 7y = 14 Distributive prop. of multiplication
4x + 7y = 2 then cancel -7y and 7y
-31x = 16 add the 2 equations
x= 16/-31 divide 16 by -31 then you'll get x
Then substitute 16/-31 in any of the two equations, you'll get y.
2007-02-24 10:48:27 · answer #1 · answered by J.B. 2 · 0⤊ 1⤋
5x+y=-2
4x+7y=2
-35x - 7y = 14
-31x = 16
x = -16/31
5(-16/31) + y = -2
-80/31 + y = 2
y = 142/31
4(-16/31) + 7(142/31) = 2
-64/31 + 994/31 = 2
930/31 = 2
30 = 2.
Oh well. Good luck.
2007-02-24 18:45:00 · answer #2 · answered by Anonymous · 0⤊ 0⤋
x = -16/31, y = 18/31
Doug
2007-02-24 18:54:29 · answer #3 · answered by doug_donaghue 7 · 0⤊ 0⤋