What two numbers multiply to -639 and add up to 638?

Here we answer the question: "What two numbers multiply to -639 and add up to 638?"

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 638:

-1 × 639 = -639
-1 + 639 = 638

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

x² + 638x - 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 638, you know that the following is true:

x² + 638x - 639 = (x - 1 ) (x + 639)

Multiply To One Number and Add Up To Another
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