SOLUTION: An interger is 4 less than three times the second number. The product is 20. Write an equation and solve to determine the intergers.

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: An interger is 4 less than three times the second number. The product is 20. Write an equation and solve to determine the intergers.       Log On


   

Question 1164844: An interger is 4 less than three times the second number. The product is 20. Write an equation and solve to determine the intergers.
Found 2 solutions by solver91311, ikleyn:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


In the first place, the term is integer, not interger.

Let represent the second integer and then must represent the first integer.



Solve for and then calculate


John

My calculator said it, I believe it, that settles it

Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
.

Your equation is

    x*(3x-4) = 20,


as the other tutor explained you.


I will show you a trick allowing solve it mentally.


Multiply both sides by 3 (the same coefficient, which is at  "3x").  You will get

    3x*(3x-4) = 3*20 = 60.


So, 60 is presented as the product of two numbers (factors) that differ by 4.


Now think, which two integers that differ by 4 give 60 as the product.


But of course, they are 6 and 10  (or -6 and -10).


In the first case, you have 3x = 10, which does not produce integer x.


In the second case,  3x = -6,  giving an integer solution x = -2,  which is your answer.

Solved     // mentally.