# The sum of 3 numbers is 11, the product of the numbers is 24 and the sum of their squares is 53. What are the numbers, are they integers?

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Expert Answers

beckden | Certified Educator

Ok well if we have the sum of these three things, we can find a cubic equation which can be solved.

Suppose our answers are a,b and c.

(a+b+c)^2 = a^2 + b^2 + c^2 + 2(ab+ac+bc)

So (ab+ac+bc) = ((a+b+c)^2 - (a^2+b^2+c^2))/2

Now (x-a)(x-b)(x-c) = x^3 - (a+b+c)x^2 + (ab+ac+bc)x - abc

So our equation is

x^3 - (a+b+c)x^2 + ((a+b+c)^2-(a^2+b^2+c^2))/2 - abc = 0

In the case above we have

x^3 - 11x^2 + (121-53)/2x - 24 = x^3 - 11x^2 + 34x - 24

We can solve this using analytical methods to get roots = 1,4,6

Student Comments

lxsptter | Student

Actually I was looking for a general answer. The trial and error method is a no-brainer.