{5x-y=5
{5x-3y=15
a][0,-5]
b][-5,0]
c][5,1]
d][1,5]
2007-06-13 02:50:05 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Substitution Method
5x - y = 5- - - - - - -Equation 1
5x - 3y = 15- - - - -Equation 2
- - - - - - - - -
5x - y = 5
5x - y - 5x = - 5x + 5
- y = - 5x + 5
- (- 1)(y) = - (- 1)(5x) + ( - 1)(5)
- ( - y) = - (- 5x) + (- 5)
y = 5x - 5
Substitute the y value into equation 2
- - - - - - - - - - - -
5x - 3y = 15
5x - 3(5x - 5) = 15
5x -(15x - 15) = 15
5x - 15x + 15 = 15
- 10x + 15 = 15
- 10x + 15 - 15 = 15 - 15
- 10x = 0
- 10x / 10 = 0 / - 10
x = 0 / - 10
x = 0
Insert the x value into equation 1
- - - - - - - - - - -
5x - y = 5
5(0) - y = 5
0 - y = 5
- y = 5
- (- 1)(y) = - 1(5)
- (- y) = - 5
y = - 5
Insert the y value into equation 1
- - - - - - - -
Check for equation 1
5x - y = 5
5(0) - ( - 5) = 5
0 + 5 = 5
5 = 5
- - - - - - - -
Check for equation 2
5x - 3y = 15
5(0) - 3(- 5) = 15
0 - (- 15) = 15
15 = 15
- - - - - - -
Both equations balance
The solution set { 0, - 5 }
- - - - - - - -s-
2007-06-13 03:26:14 · answer #1 · answered by SAMUEL D 7 · 3⤊ 1⤋
5x - y = 5
5x - 3y = 15
Subtracting the second equation from the first,
we get 5x - y - 5x + 3y = 5 - 15
i.e. 2y = -10 or y = -10/2 = -5
and substituting that in the first equation,
5x + 5 = 5 or 5x = 0 and x = 0
so x = 0 and y = -5
2007-06-13 02:57:32 · answer #2 · answered by Swamy 7 · 0⤊ 0⤋
If you add y and subract 5 to each side of the first equation, you can get the following equation:
5x - 5 = y
Now, we can plug this in for y in the second equation to get only x's:
5x - 3(5x - 5) = 15
multiplying though...
5x - 15x + 15 = 15
subtracting 15 from each side gives us:
-10x = 0
therefore, x = 0
You can plug this back into either equation to get y = -5
[0,-5]
2007-06-13 02:56:59 · answer #3 · answered by Math Stud 3 · 0⤊ 0⤋
solve 1st equation for y, y=5x-5, and substitute into 2nd equation
5x-3(5x-5)=15
5x-15x+15=15
-10x=0
x=0, substitute back into y=5x-5 to get y=-5
answer is a
2007-06-13 02:56:19 · answer #4 · answered by hrhbg 3 · 0⤊ 0⤋
x= 0, y =-5.
2007-06-13 02:55:25 · answer #5 · answered by gab BB 6 · 0⤊ 0⤋
{5x-y=5
{5x-3y=15
From eqn 1, y = 5x - 5
Substituting this into eqn 2,
5x - 3(5x - 5) = 15
5x - 15x + 15 = 15
-10x + 15 = 15
-10x = 0
x = 0
y = 5x - 5 = 0 - 5 = -5
Your answer is a][0,-5]
2007-06-13 02:54:32 · answer #6 · answered by MamaMia © 7 · 1⤊ 1⤋
a
2007-06-13 02:53:22 · answer #7 · answered by bob_whelan1944 3 · 0⤊ 0⤋