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:

-639 and 1

Below we illustrate and prove that -639 and 1 multiply to -639 and add up to -638:

-639 × 1 = -639
-639 + 1 = -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 - 639 ) (x + 1)

To summarize, since -639 and 1 multiply to -639 and add up -638, you know that the following is true:

x² - 638x - 639 = (x - 639 ) (x + 1)

Multiply To One Number and Add Up To Another
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