4x + 2y =8
2x - 5y = 10
2007-06-04 06:28:40 · 9 answers · asked by nothingspecial 1 in Science & Mathematics ➔ Mathematics
x=2.5 y=-1
eq1 =4x + 2y =8
eq2 =2x - 5y = 10
eq1+(-2*eq2)= 12y=-12 y=-1
4x +(2*-1)=8 x=2.5=5/2
2007-06-04 06:35:57 · answer #1 · answered by xandyone 5 · 0⤊ 0⤋
4x + 2y =8
2x - 5y = 10
i suggest making the x the same. By multiplying the first equation by 2 and the second by minus 4 to get the following.
-8x+4y=16
8x+10y=-40
the -8x cancels the 8x which forms 0.
leaving you with
4y=16
10y=-40
add the two together and you should get 14y=24
to get y you need to divide 24 by 14.
then substitue y in the equation. So for the first equation it 4x+2y=8 because there is 2y you times the answer you got before. Take that away from 8 and then divide the answer you just got by 4 to get what x equals.
hope that helped
The Doctor
2007-06-05 15:29:27 · answer #2 · answered by Carl F 2 · 0⤊ 0⤋
2
2007-06-04 13:32:08 · answer #3 · answered by LMAO 2 · 0⤊ 0⤋
4x + 2y =8 (1)
2x - 5y = 10 (2)
multiply equation (2) by 2
4x + 2y =8 (3)
4x - 10y = 20 (4)
equation (3) - (4)
12y = -12
y = -1
Multiply equation(1) by 5 and equation (2) by 2
20x + 10y = 40 (5)
4x - 10y = 20 (6)
equation (5) + (6)
24x = 60
x = 60/24 = 5/2
therefore, x = 5/2 and y = -1
2007-06-08 12:21:20 · answer #4 · answered by topsyk 3 · 0⤊ 0⤋
the equations are addative
6x-3y=18
3y=-18+6x
y=-6+2x => put y into a previous equation
4x+2(-6+2x)=8 solve for x
4x-12+4x=8
8x=20
x=2.5 => put into any equation
4(2.5)+2y=8
10+2y=8
2y=-2
y=-1
check
2(2.5)-5(-1)=10
5+5=10 YAY!!
2007-06-04 13:44:03 · answer #5 · answered by hooray beer 2 · 0⤊ 0⤋
4x+2y=8 ..................(1)
2x-5y =10 .................(2)
from(1) we get 4x/2+2y/2=8/2
2x +y =4
substitute y= 4-2x= 2(2-x) in equation (2)
2x - 5[2(2-x)]=10
2x -20+10x = 10
2x +10x =10 +20
12x = 30
x=30/12=5/2
substitute x= 5/2 ..................(2)
2(5/2)-5y=10
5-5y =10
-5y =10-5
-5y =5
y= -1
thus x=5/2 and y = -1
2007-06-06 04:46:03 · answer #6 · answered by billako 6 · 0⤊ 0⤋
Label first equation as eq.1
Label second equation as eq.2
To make the x terms in eq.1 and eq.2, you need to multiply eq.2 by 2.
From this you get eq.3: 4x-10y=20
eq.1 minus eq.3:
4x+2y=8
-4x-10y=20
12y= -12, y=-1
substitute value of y into eq.1: 4x+ 2(-1)= 8
4x-2=8
x=10/4=5/2
2007-06-05 09:55:31 · answer #7 · answered by halid_16 1 · 0⤊ 0⤋
20x + 10 y = 40
4x - 10y = 20-------ADD
24x = 60
x = 60 / 24 = 5 / 2
10 + 2y = 8
2y = - 2
y = - 1
Solution: x = 5/2 , y - 1
2007-06-04 13:40:15 · answer #8 · answered by Como 7 · 0⤊ 0⤋
1st method
2x-5y=10 (*2)
4x-10y=20
4x+2y=8
(-)4x-10y=20
_______
12y=-12
y=-12/12
y=-1
4x+2y=8
4x+2(-1)=8
4x-2=8
4x=10
x=5/2
2nd method
4x+2y=8
2y=8-4x
y=4-2x
2x-5y=10
2x-5(4-2x)=10
2x-20+10x=10
12x=10+20
12x=30
x=30/12
x=5/2
2x-5y=10
2(5/2)-5y=10
5-5y=10
5-10=5y
5y=-5
y=-1
2007-06-04 13:50:37 · answer #9 · answered by c 3 · 0⤊ 0⤋