Friday

August 29, 2014

August 29, 2014

Posted by **Me** on Friday, April 9, 2010 at 3:15pm.

The sum of three numbers is 15. The sum of the first, the second, and twice the third is 20. The sum of the first, twice the second, and three times the third is 27.

This is what I did:

1st # = x

2nd # = y

3rs # = z

so

x+y+z=15

x+y+2z=20

x+2y+3z=27

then solved by elimination of z, and finally got (16,10,-1)

where is my mistake?

Where is my mistake?

- Math -
**Damon**, Friday, April 9, 2010 at 3:26pm2x+2y+2z = 30

x + y+2z = 20

---------------

x + y = 10

3x+3y+3z = 45

x +2y+3z = 27

-----------------

2x + y = 18

gives

2x+2y = 20

2x +y = 18

-----------

y = 2 (not 10)

**Related Questions**

math URGENT!!!! - i have a list of 5 different numbers. the sum of 2 of the ...

Math riddle - nine odd numbers have a sum of 243.find the sum of the first and ...

Math riddle - nine odd numbers have a sum of 243.find the sum of the first and ...

MATH - system of linear equation The sum of 3 numbers is 14 the largest is 4 ...

math - Hi, for the question, "the sum of two numbers is equal to a third number(...

Math - Use each of the numbers 7, 8, 9, 10, and 11 once and only once to fill in...

Math - Use each of the numbers 7, 8, 9, 10, and 11 once and only once to fill in...

College algebra - system of linear equation The sum of 3 numbers is 14 the ...

Math - The product of three whole numbers is 36. Five more than the sum of the ...

Math (Probability) - I've worked out the first part of the question, just need ...