two times a number plus three times another number equals 13. the sum of the two numbers is 7. what r the #'s?

Answer 1

If you know anything about 'symultaneous equations' you can use that knowledge to answer this question.

The equations are 2X + 3Y = 13 and X + Y = 7
Multiply second eq by 2 and it becomes 2X + 2Y = 14
Subtract this new equation from the first one
Result Y = -1
Substitute this in equation 2 you get X + (-1) = 7 therefore X = 8
Sub these values in first eq to see if they solve ti.
(2 x 8) = (3 x -1) = 13
18 - 3 = 13
Your numbers are 8 and negative 1. Youcan do it intuitively but mathematically is better and you can apply the principle in other situations!

Answer 2

Hi,

8 and -1

Your equations are 2x + 3y = 13 and x + y = 7
Solve by multiplying the second equation by -2. It becomes
-2x -2y = -14. Add this to the first equation and the x terms drop out, leaving y = -1. Substituting this into the second equation, ir becomes x - 1 = 7. Adding 1 to each side gives x = 8.

I hope that helps.

Answer 3

2x + 3y = 13
x + y = 7
then x = 7 - y

2 ( 7 - y ) + 3y = 13
14 - 2y + 3y = 13
14 + y = 13
y = 13 - 14
y = -1

then x = 7 - (-1)
x = 8

so: x = 8; y = - 1

Answer 4

2x + 3y =13
x + y= 7 ==> x = 7 - y

2(7-y) + 3y = 13
14 - 2y + 3y = 13
-2y + 3y = 13 - 14
y = -1
x = 7 - y ==> x = 8

Answer 5

then i must be dumb because i didnt know this was algebra. i just figured 2 x 4 + 3 x 3 = 13 and 4 + 3 = 7
sorry didnt know if u meant times as in multiply or twice and thrice.