What two numbers multiply to -643 and add up to 642?

Here we answer the question: "What two numbers multiply to -643 and add up to 642?"

The answer to your question is:

-1 and 643

Below we illustrate and prove that -1 and 643 multiply to -643 and add up to 642:

-1 × 643 = -643
-1 + 643 = 642

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

x² + 642x - 643 = 0

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

(x - 1 ) (x + 643)

To summarize, since -1 and 643 multiply to -643 and add up 642, you know that the following is true:

x² + 642x - 643 = (x - 1 ) (x + 643)

Multiply To One Number and Add Up To Another
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