What r the steps to this problem?
The sum of two numbers is 15. The sum of the larger number and twice the smaller number is -1. What are the two numbers?
2007-04-30 16:07:09 · 11 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
let the numbers be x and y, where x is the smaller.
x + y = 15
y + 2x = -1
I'd use elimination/combinations for this one, it's a piece of cake.
-x - y = -15
2x + y = -1
x = -16
-16 + y = 15
y = 31
2007-04-30 16:11:03 · answer #1 · answered by atmtarzy 2 · 1⤊ 0⤋
You have to convert the information to simultaneous equations.
Let x and y be the numbers
x + y = 15 ie sum of 2 numbers
x + 2y = -1
Subtracting the two equations to eliminate x
y = -1-15 = -16
Substituting y = -16 in the first equation,
gives x = 31
The numbers are 31 and -16
The only thing that would have screwed us over in this problem is if y turned out to be greater than x, because in the second equation we assumed that y was the smaller number. Do you see that?
2007-04-30 16:12:04 · answer #2 · answered by Dr D 7 · 2⤊ 1⤋
x > y
(1) x + y = 15 --> y = 15 - x
(2) x + 2y = -1
Plug in the value of y from (1) into (2)
x + 2 (15 - x) = -1
x + 30 - 2x = -1
x - 2x = -1 - 30
- x = -31 --> x = 31
Plug the value for x back into (1)
31 + y = 15
y = 15 - 31 = -16
2007-04-30 16:15:10 · answer #3 · answered by sweetgurl_88_99 1 · 0⤊ 1⤋
X + Y= 15
X+2Y= -1
Y=15-X
X+2(15-x) = -1
X+30-2X= -1
-X=-31
X= 31
Y= 15-X
Y= 15-31
Y= -16.
Following the system of equations above the two numbers are 31, and -16.
2007-04-30 16:16:16 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Let x be the larger number and y the smaller number.
Then x +y = 15
and x + 2y = -1
Subtract the first equation from the second
then y = -16, x = 31.
2007-04-30 16:12:07 · answer #5 · answered by steiner1745 7 · 1⤊ 1⤋
x+y=15 and x+2y=-1 so in the first equation x=15-y then
(15-y)+2y=-1
15+y=-1
y=-16
Then
x+(-16)=15
x-16=15
x=31 So then the two numbers are 31 and -16
2007-04-30 16:15:28 · answer #6 · answered by Rusty 4 · 0⤊ 1⤋
you can list 2 equation
x+y=15
x+2y=-1
so you can get the x=31 and y=-16
2007-04-30 16:13:15 · answer #7 · answered by Xu D 2 · 0⤊ 1⤋
x+y = 15
let x be the larger number:
x+2y= -1
from the first eqn, we know that x=15-y
pluggin this into the second eqn:
(15-y) + 2y = -1
y+15=-1
y= -16
plugging this value back into the first equation:
x-16 = 15
x=31
so x=31, y= -16
2007-04-30 16:11:41 · answer #8 · answered by horrid 3 · 0⤊ 0⤋
If something is 40% smaller, you basically subtract 40%. So 40% of 40 energy is sixteen: you are trying this via multiplying 40 via 0.4. the respond could be 40 - sixteen = 24 A shorter way could basically be to multiply via 40 via 0.6, for the reason that's a million-0.4.
2016-10-14 05:42:14 · answer #9 · answered by ? 4 · 0⤊ 0⤋
x is larger number, y is smaller number
x+y=15
x+2y=-1
subtract the two equations simultaneously(same time)
-y=16
y=-16
plug it back in and solve x
x=31
2007-04-30 16:11:59 · answer #10 · answered by UnknownD 6 · 0⤊ 1⤋