Solve the system of equations using the substitution method.
If the answer is a unique solution, present it as an ordered pair: (x, y). If not, specify whether the answer is “no solution” or “infinitely many solutions.”
-7x + y = 4
2x + 8y = 0
2007-04-16 13:46:34 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
do your homework
2007-04-16 13:48:55 · answer #1 · answered by BMS 4 · 0⤊ 0⤋
Must be nice to have all this time to type in your child's questions. What is your secret to success.
Snide remarks aside, multiply eqtn 1 by 8
- 56x + 8y = 32 eqtn 1a
2x + 8y = 0
Subtract eqtn 2 from eqtn 1a, then
- 58 x = 32 or x = - 16/29
Substitute in any equation 1, 1a or 2. 2 is most convenient.
- 32/29 + 8y = 0
y = 4/29
You can check it out. The ordered pair is
(-32/29,4/29)
2007-04-16 20:56:36 · answer #2 · answered by cattbarf 7 · 0⤊ 0⤋
Where are you stuck? What have you tried so far?
The usual way to handle these things is to isolate one variable, such as x=4y-7. Then substitue 4y-7 for x in the *other* equation. Solve that for y. plug that value for yinto either equation, and solve for x. There's your answer.
If you can't get a legal answer, you have no solution.
If either variable drops out, so you get something like 4=4 or 2y=2y, then you have infinitely many solutions.
2007-04-16 21:10:14 · answer #3 · answered by norcekri 7 · 0⤊ 0⤋
-7x + y = 4 (given)
y = 4 + 7x (just add 7x to both sides)
Now sub in for y (since y=4+7x, you can replace y by 4+7x in the second equation)
2x + 8(4 + 7x) = 0
Solve this equation for x. Then plug the value you get back into either equation to get y.
2007-04-16 20:55:15 · answer #4 · answered by themissy11 1 · 0⤊ 0⤋
set -7x+y = 4 equal to y
so y = 7x +4
then substitue 7x +4 in place of y in your second equation
2x + 8(7x+4) = 0
2x +56x +32 = 0
58x = -32
x = - 16/29
then use this to find y in your other original equation
y =7(-16/29) + 4
y = 4/29
2007-04-16 21:01:13 · answer #5 · answered by WeepingHead 2 · 0⤊ 0⤋
y= 4+7x
2x+8(4+7x) = 0
2x +32 +56x = 0
58x = -32
x = -32/58 = -16/29
y =4 +7(-16/29) = 4 - 112/29 =1 25/29
(-16/29 , 1 25/29)
2007-04-16 20:54:26 · answer #6 · answered by ironduke8159 7 · 0⤊ 0⤋
This look ssuspiciously like homework to me. If I were having trouble with Algebra, I would talk to my parent or gaurdian about tutoring. If you're in high school, the office probably has a list of student tutors that you can look at.
2007-04-16 20:57:44 · answer #7 · answered by Anonymous · 0⤊ 0⤋
y can be 3 and x can be 12 this is the answer to the second one
don't listen to anyone about putting tis on answers GoOD lUCK
2007-04-16 20:52:56 · answer #8 · answered by Anonymous · 0⤊ 0⤋