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2 numbers are first added together and then multiplied together. The numbers added together = 18 and the numbers multiplied together = 45. What are the 2 numbers?


Question asked by: knowitall

The numbers are 15 and 3.
By: Unknown
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The two numbers are 15 & 3... Doesn't matter which order you choose to put them in, it'll still work. Here's how I came up with it using algebra: Firstly note: a x b = 45 therefore: b = 45/a (equation 1) Second, note that: a + b = 18 (equation 2) now we can substitute equation 2 into equation 1: a + (45/a) = 18 rearraning: a - 18 + (45/a) = 0 multiply by factor of a: a^2 - 18a + 45 = 0 (equation 3) Thirdly, note that equation 3 is a solveable quadratic equation with real solutions of a=3 and a=15. Substituting either solution back into equation 1 gives: a=3 and b=15 or a=15 and b=3 QED.
By: Sacha001

Date of comment: Thu, Jul 15th 2010

Yeah, I think the person asking the question wants to see the algebraic arithmatic actually working out the answer!
By: sb70520

Date of comment: Sun, Jun 13th 2010

First no is 15 and secon no is 3 when you will add 15+3=18 when you will multiply 15*3=45
By: susanta

Date of comment: Wed, Jul 22nd 2009

15 + 3
By: Alexar23

Date of comment: Tue, Dec 4th 2007

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numbers  multiplied  added  

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