2006-07-03 05:22:12 · 11 answers · asked by cityturtleblue 2 in Education & Reference ➔ Other - Education
y= 7 - 3x and y = 4x - 21
equate the two equations: 7-3x = 4x - 21
therefore 28=7x
x=28/7
x=4
therefore y=7 - 3(4)
y = -5
2006-07-03 05:28:06 · answer #1 · answered by Mezee 3 · 1⤊ 0⤋
3x + y = 7 4x - y = 21 3x + y = 7 y = 7 - 3x 4x - y = 21 4x - (7 - 3x) = 21 4x - 7 + 3x = 21 4x + 3x = 21 + 7 7x = 28 x = 28/7 x = 4 4x - y = 21 4(4) - y = 21 -y = 21 - 16 -y = 5 y = 5/-a million y = -5 ? x = 4 , y = -5 (4,-5)
2016-11-05 21:13:03 · answer #2 · answered by valderrama 4 · 0⤊ 0⤋
3x+y=7 4x-y=21
3x = 7 - y 4x = 21 + y
x = 7 - y / 3 x = 21 + y / 4
7 - y / 3 = 21 + y / 4
28 - 4y = 63 + 3y
28 - 63 = 3y + 4y
-35 = 7y
7y = -35
y = -35 / 7
y = -5
substitute y into 3x + y = 7
3x + (-5) = 7
3x - 5 = 7
3x = 7 + 5
3x = 12
x = 12 / 3
x = 4
[[ y = -5, x = 4 ]]
2006-07-03 05:38:25 · answer #3 · answered by K 4 · 0⤊ 0⤋
This is solving for two variables using a system of simultaneous equations. In this case, by using the Addition Property, we can add the equations together, resulting 7x=28. Therefore, x=4. Using the Substitution Property, substitute x=4 into either equation to solve for y. y=-5.
2006-07-03 05:31:39 · answer #4 · answered by Vanessa 4 · 0⤊ 0⤋
3x+y=7;4x-y=21 ;; solve for x by adding them together to get 7x=28: therefore x=4 then substitute in orig eq.:to get y= -5
2006-07-03 05:33:52 · answer #5 · answered by paulofhouston 6 · 0⤊ 0⤋
add the two equations:
7x=28
x=4
put the value of x in any of the equations:
3*4 +y=7
y=-5
2006-07-03 05:31:08 · answer #6 · answered by bhaiyu 2 · 0⤊ 0⤋
the answer is
x= 4
y= -5
2006-07-03 05:29:48 · answer #7 · answered by quikboy 7 · 0⤊ 0⤋
3x+y=7.....x=(7-y)/3
4x-y=21....x=(21+y)/4
now,
(7-y)/3=(21+y)/4
now solve this...
2006-07-03 05:30:43 · answer #8 · answered by Anonymous · 0⤊ 0⤋
You have to even the sides so...
yeah!
2006-07-03 05:26:11 · answer #9 · answered by miapia87 2 · 0⤊ 0⤋
it's an algabra question!
~*Alyssa*~
2006-07-03 05:25:37 · answer #10 · answered by Anonymous · 0⤊ 0⤋