how do you do this? i can't figure it out, and neither can my friends. you have to solve for x and y using substitution.
15....18.....................1.......2
__ + __ = 72 & __ + __ = - 4
x........y.......................x........y
please help! ( the dots don't mean anything )
2007-04-16 09:34:23 · 2 answers · asked by ♥♫ Never Too Late ♫♥ 7 in Science & Mathematics ➔ Mathematics
the last part is supposed to be 1 over x plus 2 over y
2007-04-16 09:35:05 · update #1
ok, here's the problem in words: 15 over x plus 8 over y equals 72. 1over x plus 2 over y equals negative 4. solve the equations by using substitution
2007-04-16 09:40:59 · update #2
thank you philo! thank you! my teacher never taught us how to do that. now i can graph it!
2007-04-16 09:53:37 · update #3
15/x + 18/y = 72
1/x + 2/y = -4
let a = 1/x and b = 1/y.
15a + 18b = 72
a + 2b = -4
15a + 18b = 72
9a + 18b = -36
6a ......... = 108
a = 18.
18 + 2b = -4
2b = -22
b = -11
x = 1/18, y = -1/11
2007-04-16 09:41:06 · answer #1 · answered by Philo 7 · 0⤊ 1⤋
I don't think the question is very clear.
Once you clearly define the question, and you have 2 independent equations with 2 unknowns, you CAN solve for x and y.
2007-04-16 16:42:38 · answer #2 · answered by Dr D 7 · 0⤊ 0⤋