2x + y = 5
x + y = -2
step by step
solve this
im VERY slow at comprehending
2007-11-14 16:32:30 · 9 answers · asked by hello 2 in Science & Mathematics ➔ Mathematics
IT HAS TO BE ELIMINATION BY ADDITION!!!!!!
GEEZ!
2007-11-14 16:41:50 · update #1
2x + y = 5
x + y = -2
take the 2nd equation and solve for y (note that you could solve for y in the first equation instead)
y= -2 + -x
substitute what we just found in for y in the first equation:
2x + -2 + -x = 5
x + -2 = 5
x= 5 + 2
x= 7
now take either equation and input 7 in where you see an x
7 + y = -2
solve for y
y= -9
Answer: y= -9, x= 7
2007-11-14 16:52:27 · answer #1 · answered by Matty B 3 · 0⤊ 1⤋
OK! There are many ways to solve this, but the simplest one is:
=======
2x + y = 5 (1)
x + y = -2 (2)
(1) - (2) (substract (1) from (2))
<=> 2x + y - x - y = 5 - (-2)
<=> x=7
x+y= -2
<=> 7 + y = -2
<=> y= -9
2007-11-14 16:39:43 · answer #2 · answered by the_black_pearl_vn 2 · 0⤊ 0⤋
All of the answers seem very busy to me.
The concept is that you want to multiply each part of ONE of the equations by a number - let's say the second equation by -2 to allow one of the variables to be eliminated when the two equations are added together.
2x + y = 5
x + y = -2 (Why multiply by -2??)
because it gives you:
-2x -2y = 4
which you can add to the first equation:
2x + y =5 . . . to get
0x (which is zero) -y = 9
y = -9
Then substitute the answer into either equation for y and solve for x
2x -9 = 5
2x = 14
x = 7
(7, -9)
2007-11-14 16:53:35 · answer #3 · answered by Mark P 2 · 0⤊ 1⤋
Subtract one equation from the other.
2x + y = 5
- (x + y = -2)
2x + y = 5
-x - y = 2
Now, the y's cancel out and you are left with
x = 7
Substitute x back into one of the original equations to find the value of y.
2(7) + y = 5
y = -9.
2007-11-14 16:59:16 · answer #4 · answered by Nitro 5 · 0⤊ 1⤋
2x + y = 5 ....(1)
x + y = -2 ....(2)
(1) - (2)
(2x + y) - (x + y) = 5 - (-2)
2x + y - x - y = 5 + 2
x = 7
Sub x = 7 into (2)
7 + y = -2
y = -2 -7
y = -9
2007-11-14 16:40:15 · answer #5 · answered by Chan A 3 · 0⤊ 1⤋
I would multiply the bottom equation by -1
2x +y = 5
-x - y = 2
-------------
x = 7
7 + y = -2
y = -9
2007-11-14 16:37:18 · answer #6 · answered by Ms. Exxclusive 5 · 0⤊ 0⤋
2x + y = 5
-x - y = 2---------ADD
x = 7
7 + y = - 2
y = - 9
x= 7 , y = - 9
2007-11-14 20:24:13 · answer #7 · answered by Como 7 · 2⤊ 1⤋
2x+y= 5
(-)x+y= -2
----------------
2x+y= 5
-x-y= +2
-----------------
2x-x=5+2
x=7
now plug 7 in x.
x+y= -2
7+y= -2
y= -2-7
y= -9
.:. x=7; y= -9
2007-11-14 16:44:57 · answer #8 · answered by Anonymous · 0⤊ 2⤋
1. 2x + y = 5
-x - y = 2 (make this neg then subtract both)
-----------------------
x = 3
go back plug in 3 for x
(3) + y =-2
-------------------
y = -5
2007-11-14 16:39:40 · answer #9 · answered by k d 1 · 0⤊ 1⤋