What two numbers multiply to 639 and add up to 640?

Here we answer the question: "What two numbers multiply to 639 and add up to 640?"

The answer to your question is:

1 and 639

Below we illustrate and prove that 1 and 639 multiply to 639 and add up to 640:

1 × 639 = 639
1 + 639 = 640

Are you asking because you are trying to figure out how to factor the following quadratic equation?

x² + 640x + 639 = 0

If so, the solution to factor the quadratic equation above is:

(x + 1 ) (x + 639)

To summarize, since 1 and 639 multiply to 639 and add up 640, you know that the following is true:

x² + 640x + 639 = (x + 1 ) (x + 639)

Multiply To One Number and Add Up To Another
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