2007-06-10 15:08:48 · 5 answers · asked by RABBIT 1 in Education & Reference ➔ Homework Help
x+y=7 (i) --> x = 7-y (iii)
x-y=9 (ii)
Substitute (iii) into (ii):
(7-y) - y = 9
7 - 2y = 9
-2y = 2
y = -1
Substitute the value for y into (i):
x + (-1) = 7
x = 8
2007-06-10 15:13:37 · answer #1 · answered by evelyn~* 1 · 0⤊ 0⤋
This is very easy because you have a positive and a negative y which when added will cancel each other out. Now you have x + x which is 2x and 7 + 9 which is 16. 2x = 16 Divide by 2 and x = 8......Substitute 8 for x in either equation and you get y = -1.
2007-06-10 15:18:18 · answer #2 · answered by dpirsq2 5 · 0⤊ 0⤋
x +y=7
x-y=9 the y's cancel out so you have
2x=16 divide by 2
x=8 Check your work by replacing the 8 for x to solve for y.
8+y=7 add -8 to both sides
y= -1 .
2007-06-10 15:14:53 · answer #3 · answered by txmama423 3 · 0⤊ 0⤋
x+y=7
x-y=9
1) to find x, you need to get rid (or to eliminate) y. in order to do that, you have to add y to to each equation. then, you end up with 2x=7+9, which 2x=16. therefore, x=8
2)to find y, you can substitute in x=8 to any of the equation above
x-y=9
8-y=9
-y=1
y=-1
therefore, the answer is (8, -1)
2007-06-10 15:20:05 · answer #4 · answered by Krystal 2 · 0⤊ 0⤋
x+y=7
x-y=9
Add the first equation to the second equation
2x = 16
x = 8
8 - y = 9
y = -1
.
2007-06-10 15:12:17 · answer #5 · answered by Robert L 7 · 0⤊ 0⤋