2007-05-11 10:06:57 · 7 answers · asked by Ashley H 1 in Science & Mathematics ➔ Mathematics
X= -9
Y=5
2007-05-11 10:15:14 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Multiply the second equation by four then subtract the first from it.
4x + 9y = 9 (1)
4x + 20y = 64 (2)
(2) - (1) 11y = 55 => y = 5
x + 5y = 16 => x = -9
2007-05-11 10:13:54 · answer #2 · answered by qspeechc 4 · 0⤊ 0⤋
4x+9y=9
x+5y=16
you have to times the second equation by -4 in order to cancel anything out. this will cancel out the 4x on top and the -4x on the bottom cause 4x+(-4x)=0
then you have:
9y=9
-20=-64 (because you times by -4)
then you do 9y+(-20) and 9+(-64)
which equals -11y which equals -55
so now you have -11y=-55
y=5
then you substitute y into any equation
x+5(5)=16
x+25=16
x=-9
so the answer will be x=5 y=-9
2007-05-11 10:30:12 · answer #3 · answered by me 1 · 0⤊ 0⤋
4x + 9y = 9
-4(x + 5y = 16)
4x + 9y = 9
+ -4x -20y = -64
---------------------------
-11y = -55
--- ----
-11 -11
y = 5
4x + 9y = 9
4x + 9(5) = 9
4x + 45 = 9 - 45
4x = -36
-- ---
4 4
x = -9
Steps:
1.) multiply by -4 to cancel out the x terms
2.) Add
3.) Solve for y
4.) Sub y in one of the equations
5.) Re-arrange and solve for x
2007-05-11 17:46:47 · answer #4 · answered by Anonymous · 0⤊ 0⤋
4x + 9y = 9
- 4x - 20y = - 64----ADD
- 11y = - 55
y = 5
x + 25 = 16
x = - 9
x = - 9 , y = 5
2007-05-11 10:21:12 · answer #5 · answered by Como 7 · 0⤊ 0⤋
from second equation
x=16-5y
4(16-5y)+9y=9
64-20y+9y=9
64-11y=9
-11y=9-64
-11y=-55
y=5
for x
x=16-5y
x=16-25
x=-9
x=-9
y=5
2007-05-11 10:33:48 · answer #6 · answered by sassy_girl 3 · 0⤊ 0⤋
x+5y=16
x=16-5y
4x+9y=9
4(16-5y)+9y=9
64-20y+9y=9
-11y=9-64
-11y=-55
y=-55/-11
y=5
x+5y=16
x+5(5)=16
x+25=16
x=16-25
x=-9
2007-05-11 15:50:21 · answer #7 · answered by sam 3 · 0⤊ 0⤋