SOLUTION: Use te clue to find the secret two-digit number. The sum of the digits is 9. The product of the digits is 18. The number is between 40 and 90. What is the number?

Click here to see ALL problems on Finance

Question 303960: Use te clue to find the secret two-digit number. The sum of the digits is 9. The product of the digits is 18. The number is between 40 and 90.
What is the number?
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
The sum of the digits is 9. The product of the digits is 18. The number is between 40 and 90.
What is the number?
:
Let 10x + y = the two digit number
:
"The sum of the digits is 9."
x + y = 9
y = (9-x)
:
The product of the digits is 18.
x * y = 18
Replace y with (9-x)
x(9-x) = 18
-x^2 + 9x = 18
-x^2 + 9x - 18 = 0
Multiply by -1 to change the signs
x^2 - 9x + 18 = 0
Factors easily to
(x-6)(x-3) = 0
x = 6, (no. is greater than 40)
then
y = 3
:
The number is between 40 and 90.
What is the number? It's 63