// End script hiding -->
SOLUTION: What is the only prime number that is the sum and difference of two primes?
Algebra
->
Customizable Word Problem Solvers
->
Numbers
-> SOLUTION: What is the only prime number that is the sum and difference of two primes?
Log On
Ad:
Over 600 Algebra Word Problems at edhelper.com
Ad:
Mathway
solves algebra homework problems with step-by-step help!
Word Problems: Numbers, consecutive odd/even, digits
Word
Solvers
Solvers
Lessons
Lessons
Answers archive
Answers
Immediate math help from PAID TUTORS
. (paid link)
Click here to see ALL problems on Numbers Word Problems
Question 269079
:
What is the only prime number that is the sum and difference of two primes?
Answer by
mananth(14512)
(
Show Source
):
You can
put this solution on YOUR website!
What is the only prime number that is the sum and difference of two primes?
let one digit be x and the other be y
xy=7 --------------1
x+y=8--------------2
multiply equation 2 by y
xy+y^2 = 8y ---------- 3
subtract 2 from 1
-y^2 = 7-8y
y^2-8y+7=0
y^2-7y-y+7=0
y(y-7)-1(y-7)=0
(y-1)(y-7)=0
y= 7 or 1
y cannot be in the tens place because the number is less than 50.
So the number will be 17