What two numbers multiply to -400 and add up to -399?

Here we answer the question: "What two numbers multiply to -400 and add up to -399?"

The answer to your question is:

-400 and 1

Below we illustrate and prove that -400 and 1 multiply to -400 and add up to -399:

-400 × 1 = -400
-400 + 1 = -399

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

x² - 399x - 400 = 0

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

(x - 400 ) (x + 1)

To summarize, since -400 and 1 multiply to -400 and add up -399, you know that the following is true:

x² - 399x - 400 = (x - 400 ) (x + 1)

Multiply To One Number and Add Up To Another
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