anyone know how to solve this? you gotta use elimination.
2007-09-17 14:21:58 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
A:3x-10y=-25
B:4x+40y=20
Ax4=4(3x-10y)=(-25 )(4)
so 12x-40=-100
+ 4x+40y=20
------------------------------
16x=-80
so,x=-5,y=1
2007-09-17 14:29:47 · answer #1 · answered by Hang 3 · 0⤊ 0⤋
4x + 40y = 20 and then plus or minue 3x - 10y = -25. In this case you need to multiply. Take the second and multiply by four and then add to the first equation (by subtracting you would have a double negative).
4x + 40 y = 20 plus 12x - 40 y = -100 So then 16 x = 80. 80 divided by 16 equals 5. Then substitute back in to get y.
2007-09-17 14:32:10 · answer #2 · answered by wildfreedom13 3 · 0⤊ 0⤋
[3x-10y=-25]4
4x+40y=20... add the terms and you will get
12x-40y=-100
4x+40y=20
__________
16x =-80
x =-5... then substitute value of x
3(-5)-10y=-25
-15+25=10y
y=1
2007-09-17 14:30:24 · answer #3 · answered by criselda 3 · 0⤊ 0⤋
4x + 40y = 20
4x = 20 - 40y
x = 5 - 8y
3x - 10y = -25
3(5-8y) - 10y = -25
15 - 24y - 10y = -25
-34y = -40
y= 40/34 = 20/17
x=5 - 8y = 5 - 160/17 = - 75/17
2007-09-17 14:33:05 · answer #4 · answered by Anonymous · 0⤊ 0⤋
ehehehe
put them on top of each other so you can see... multiply one of the equations so that either x or y is opposite......
like if they were -666 or 666
so yours.. you could multiply the first equation by four, everything, the 3x, -10y, and -25,then eliminate the 40y and -40y and solve
2007-09-17 14:28:36 · answer #5 · answered by w 2 · 0⤊ 0⤋
Put 3x-10y=-25 on top and multiply everything in the top equation by 4 and the bottom equation by -3 and it will look like this:
12x-40y=-100
-12x-120y=-60
Add the top equation to the bottom equation. The x's will cancel out to give you zero.
You will be left with:
-160y=-160
Finally, divide each side by -160 and y=1.
2007-09-17 14:34:23 · answer #6 · answered by tmunson24 2 · 0⤊ 1⤋
3x-10y= -25.......(eqn 1)
4x+40y=20........(eqn 2)
Multiplying eqn 1 by 4 and eqn 2 by 3
12x-40y= -100
12x+120y=60
(subtracting0 -160y= -160 y=1
Plugging y in eqn 1
3x-10= -25
3x= -25+10= -15
x= -15/3 = -5
x= -5 and y=1 ans
2007-09-17 14:33:59 · answer #7 · answered by alpha 7 · 0⤊ 0⤋
12x - 40y = - 100
4x + 40y = 20------ADD
16x = - 80
x = - 5
- 20 + 40 y = 20
40y = 40
y = 1
x = - 5 , y = 1
2007-09-19 05:22:00 · answer #8 · answered by Como 7 · 1⤊ 0⤋