SOLUTION: what multiplied by what gives you 54 and adds up 21

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Question 405827: what multiplied by what gives you 54 and adds up 21
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
I think you want two numbers x and y such that

xy = 54
x+y = 21

Two ways to do this:

If you can factor 54 in your head, and know that 54 = 18*3, you can conclude that 18 and 3 are the numbers.

Or, letting y = 21 - x (from the second equation, we substitute and obtain a quadratic:

x%2821+-+x%29+=+54 --> -x%5E2+%2B+21x+-+54+=+0 --> x%5E2+-+21x+%2B+54+=+0. Either by the quadratic formula or by factoring we get x = 18 or x = 3, and both these solutions are equivalent since one implies the other.