What two numbers multiply to -641 and add up to 640?

Here we answer the question: "What two numbers multiply to -641 and add up to 640?"

The answer to your question is:

-1 and 641

Below we illustrate and prove that -1 and 641 multiply to -641 and add up to 640:

-1 × 641 = -641
-1 + 641 = 640

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

x² + 640x - 641 = 0

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

(x - 1 ) (x + 641)

To summarize, since -1 and 641 multiply to -641 and add up 640, you know that the following is true:

x² + 640x - 641 = (x - 1 ) (x + 641)

Multiply To One Number and Add Up To Another
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