Solve by the substitution method. I know that the answer is (3,-2) but how do you get it??
2006-10-11 03:33:34 · 14 answers · asked by manda9287 1 in Science & Mathematics ➔ Mathematics
From second equation
-y = 17 - 5x
y = 5x - 17
Substituting in first equation
4x -3(5x - 17) = 18
4x -15x + 51 = 18
-11x = -33
x = 3
Substituting in second equation
y = 5 * 3 - 17
y = 15 - 17
y = -2
Solution x = 3 and y = -2
2006-10-11 03:38:11 · answer #1 · answered by fsm 3 · 0⤊ 0⤋
(2) 5x - y = 17
-y -y
5x = 17 -y
/5 /5
x = (17-y)/5
(1) 4x - 3y = 18 here just substitute the x with what I got above...
Simplify this: 4((17-y)/5) - 3y = 18 Otherwise if you have a graphing calculator that might help.
Do it, you know you can and you know this is last minute homework, I did the all the hard stuff... If it doesn't work, sorry. I tried. Good luck!
2006-10-11 10:42:03 · answer #2 · answered by Angel-Errr-uMMM? 2 · 0⤊ 0⤋
( 5x-y=17 ) x 3 = 15x-3y-51, then use the substitute method with the first equation, you'll get 11x = 33, so x = 3. Then just put it in one of the equation you earlier like 5(3)-y=17, so y = -2. In the end the answer is (3,-2)
2006-10-11 10:39:04 · answer #3 · answered by DayDay 3 · 0⤊ 0⤋
This is easy.
1) Get y to the right side in equation #2. then subtract both sides by 17, so that the equation is now 5x - 17 = y (now equation #3)
2) Substitute equation #3 into equation #1,subtract both sides by 18, so that it is now 4x - 3(5x - 17) - 18= 0
3) Simplify, so that now you get -11x+33
4) Solve for X, x = 3
5) Sub x into equation #3 (5(3)-17=y)
6)y = -2
Therefore, the solution is (3,-2)
In step by step format
2006-10-11 10:44:07 · answer #4 · answered by FeZbOy 1 · 0⤊ 0⤋
To solve by substitution you have to solve one equation for either x or y. It's easiest to solve the 2nd one for y.
So -y=17+5x the get rid of the negative so y= -17+5x
Plug in the the new equation in the 1st for y.
so 4x-3(-17-5x)=18 and solve for x.
once you have x, plug x in to solve for y.
2006-10-11 10:41:07 · answer #5 · answered by shortcake85 1 · 0⤊ 0⤋
First solve one of the equations for one of the variables. I will begin with the 2nd equation because I can see that it will be easy to solve for y (no fractions)..
5x-y = 17
-y = -5x +17
y = 5x - 17
Now, I have a value for y that I can "plug" into the first equation
4x - 3y = 18
4x - 3(5x - 17) = 18
Now, I solve for x
4x - 15x + 51 = 18
-11x = -33
x = 3
Now, I have a value for x that I can plug into either of the original equations to find the value of y.
5x - y = 17
5(3) - y = 17
15 - y = 17
-y = 2
y = -2
The answer is (3, -2) like you said.
2006-10-11 10:40:37 · answer #6 · answered by kevvsworld 3 · 0⤊ 0⤋
1) 4x-3y=18
2) 5x-y=17
Let's rearrange equation #2.
y=5x-17
So, plug this into equation 1.
4x - 3(5x-17) = 18
4x -15x +51 = 18
-11x + 51 = 18 (Rearranged)
11x = 33
x = 3
Since x = 3, solve for y in one of the equations.
I'll use the second one.
5(3)-y =17
15-y=17
y= -2
(3, -2)
Regards,
Mysstere
2006-10-11 10:38:54 · answer #7 · answered by mysstere 5 · 0⤊ 0⤋
15x - 3y = 51 [3(5x - y = 17)]
4x - 3y = 18
11x = 33
x = 3
5(3) - y = 17 (Subsitute x into 5x - y = 17)
y = -2
Therefore (x,y) = (3, -2)
2006-10-11 14:52:59 · answer #8 · answered by insurebizz 2 · 0⤊ 0⤋
4x - 3y = 18......(1)
5x - y = 17......(2)
y = 5x - 17......(3)
Sub (3) into (1)
4x - 3(5x - 17) = 18
4x - 15x + 51 = 18
11x = 51 - 18
x = 3
Sub x=3 into (3)
y = 5(3) - 17
y = 15 - 17
y = -2
2006-10-12 14:14:10 · answer #9 · answered by yukki_b 2 · 0⤊ 0⤋
5x -y =17
y= 5x-17
Substitute in other formula
4x-3(5x-17)=18
4x-15x+51=18
-11x=18-51=133
x=3
y=5x(3)-17
y=-2
2006-10-11 10:42:00 · answer #10 · answered by Anonymous · 0⤊ 0⤋