2007-09-13 06:19:21 · 6 answers · asked by tamdayash 1 in Science & Mathematics ➔ Mathematics
5x + 2y = -15
y = 2x - 12
5x + 2(2x - 12) = -15
5x + 4x - 24 = -15
9x = 9
x = 1
y = -10
2007-09-13 06:23:55 · answer #1 · answered by gebobs 6 · 1⤊ 1⤋
5x + 2y = -15
y = 2x - 12
Substitute 2x-12 for y in the first equation and solve for x:
5x + 2(2x-12) = -15
5x + 4x - 24 = -15
9x = 9
x = 1
Substitute 1 for x in the second equation and solve for y:
y = 2(1) - 12
y = 2 - 12 = -10
So, x=1 and y =-10.
You can check these by plugging them back into both equations.
2007-09-13 06:24:33 · answer #2 · answered by Larry C 3 · 1⤊ 1⤋
First: substitute "2x-12" with "y" in the 1st equation.
5x+2(2x-12) = -15
5x+2(2x)+2(-12) = -15
5x+4x-24 = -15
9x-24 = - 15
Sec: combine "like" terms - add 24 with both sides (when you move a term to the opposite side, always use the opposite sign).
9x-24+24 = - 15+24
9x = 9
Third: isolate "x" on one side (divide both sides by 9).
9x/9 = 9/9
x = 9/9
x = 1
Fourth: substitute "1" with "x" in the 2nd equation.
y = 2(1) - 12
y = 2 - 12
y = -10
Solution: (1, -10)
2007-09-13 06:28:34 · answer #3 · answered by ♪♥Annie♥♪ 6 · 1⤊ 0⤋
5x+2y=-15 --- (1)
y=2x-12 -- (2)
use y in (1)
5x+2(2x-12)=-15
5x+4x-24=-15
9x-24=-15
9x=9
x=1
using (2)
y=2(1)-12=2-12=-10
x=1, y=-10
2007-09-13 06:36:25 · answer #4 · answered by cidyah 7 · 1⤊ 0⤋
- 15y = 5x + 2y
- 17y = 5x
y = - 5/17x
- 15y = 2x - 12
y = - 2/15x + 4/5
- 5/17x = - 2/15x + 4/5
- 75/255x + 34/255x = 4/5
- 41/255x = 4/5
x = - 204/41
y = - 2/15(- 204/41) + 4/5
y = 136/205 + 164/205
y = 60/41
Answer: x = - 204/41, y = 60/41
Proof:
5(- 204/41) + 2(60/41) = - 15(60/41)
- 1,020/41 + 120/41 = - 900/41
- 900/41 = - 900/41
2007-09-13 06:40:16 · answer #5 · answered by Jun Agruda 7 · 3⤊ 1⤋
5x+2y=-15 y=2x-12
5x+2(2x-12)=-15
5x+4x-24=-15
9x=9
x=1
Now to find y...
5(1)+2y=-15
2y=-20
y=-10
The answer is (1,-10)
2007-09-13 06:22:43 · answer #6 · answered by Kaylin 4 · 0⤊ 1⤋