5x + 9y = -17
-4x + y = 30
2007-08-25 07:03:59 · 7 answers · asked by Jack M 1 in Science & Mathematics ➔ Mathematics
20x + 36y = - 68
-20x + 5y = 150----ADD
41y = 82
y = 2
5x + 18 = - 17
5x = - 35
x = - 7
x = - 7 , y = 2
2007-08-25 07:54:17 · answer #1 · answered by Como 7 · 1⤊ 0⤋
Original problem:
5x + 9y = -17
-4x + y = 30
Step 1: Put y by itself on the bottom (add 4x to each side for the bottom equation)
5x + 9y = -17
y = 30 +4x
Step 2: Plug the bottom equation in for y at the top
5x + 9 (30 + 4x) = -17
Step 3: Simplify
5x + 270 + 36x = -17
41x + 270 = -17
41x = -287
x = -287 % 41
x = -7
Step 4: Find y using the original equation
-4(-7) + y = 30
28 + y = 30
y = 2
2007-08-25 14:13:35 · answer #2 · answered by dabomb18359 2 · 0⤊ 1⤋
take the 2nd equation ( -4x +y=30) and add the 4x to make it y= 4x+30. Then take the 1st equation (5x +9y=-17) and substitute the y. 5x + 9 (4x+30) = -17 and get 5x+36x+270=-17 and solve. 41x= -287. divide. x= -7. now substitute again. y= 4(-7) +30. y=-28 +30. y= 2. Make a sentence. X= -7 and Y = 2. Now ur done! :)
2007-08-25 14:12:16 · answer #3 · answered by Anonymous · 0⤊ 0⤋
In the second equation y = 4x + 30 substitute in the first equation: 5x+9(4x+30)=-17
41x+270=-17
41x = -287
x=-7
so y = 4(-7) + 30 = 2
2007-08-25 14:09:50 · answer #4 · answered by chasrmck 6 · 0⤊ 0⤋
-4x + y = 30
y = 30+4x
5x + 9(30+4x) = -17
5x +270 +36x = -17
41x = -270-17 = -287
x = -7
y=30+4(-7)=30-28=2
x=-7, y=2
2007-08-25 14:11:15 · answer #5 · answered by skipper 7 · 0⤊ 0⤋
y=30+4x---------1)
putting the value of y in the eq.
5x +9(30+4x)=-17
5x +270 +36x =-17
41x =-17-270
x=-287/41
x=-7
putting the vaue of x in i)
y=30 +4(-7)
=30-28
=2
so { x, y}={-7,2}
2007-08-25 14:09:37 · answer #6 · answered by sv1973 2 · 0⤊ 0⤋
Solve one of the equations for x, then plug in x to the other equation. You'll get the answer for y, then you should know how to get the answer for x.
Good Luck!
2007-08-25 14:08:24 · answer #7 · answered by nailcikcia 3 · 0⤊ 0⤋