5x+7y=1
4x-2y=16
2007-01-01 10:37:02 · 4 answers · asked by eduardo r 1 in Science & Mathematics ➔ Mathematics
5x + 7y = 1 ..... (1)
4x - 2y = 16 .....(2)
Note that the y's are opposite in signs so I will eliminate the y's
Equation (1) * 2 + equation (2) * 7
(10x + 28x) + (14y + -14y) = 1*2 + 16*7
ie 38x = 114
So x = 114/38
= 3
Substitute into equation (1)
5*3 + 7y = 1
7y = -14
y = -2
check in equation (2)
4x - 2y = 4*3 - 2*-2 = 16 YESSSSSSSSSS!!!!!!!!!!!!!
So the solution is x = 3 y = -2
2007-01-01 10:52:40 · answer #1 · answered by Wal C 6 · 0⤊ 0⤋
first eliminate one of the variables by finding the LCM for the coefficients...
so...
20x + 28y = 4
20x - 10y = 80
Then eliminate the coefficient by subtracting the two equations.
- 38y = 76... y = -2
Then plug the value you just got into one of the original equations.
5x - 14 = 1
5x = 15
x=3
So plug in x and y values into the original equations to see if you are right.
2007-01-01 18:41:46 · answer #2 · answered by Sam L 2 · 0⤊ 1⤋
Nope, I've done too many tonight already...
2007-01-01 18:41:11 · answer #3 · answered by K V 3 · 0⤊ 1⤋
What kind of help do you need?
2007-01-01 18:39:06 · answer #4 · answered by modulo_function 7 · 1⤊ 1⤋