What two numbers multiply to -399 and add up to 398?

Here we answer the question: "What two numbers multiply to -399 and add up to 398?"

The answer to your question is:

-1 and 399

Below we illustrate and prove that -1 and 399 multiply to -399 and add up to 398:

-1 × 399 = -399
-1 + 399 = 398

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

x² + 398x - 399 = 0

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

(x - 1 ) (x + 399)

To summarize, since -1 and 399 multiply to -399 and add up 398, you know that the following is true:

x² + 398x - 399 = (x - 1 ) (x + 399)

Multiply To One Number and Add Up To Another
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