What two numbers multiply to -400 and add up to 9?

Here we answer the question: "What two numbers multiply to -400 and add up to 9?"

The answer to your question is:

-16 and 25

Below we illustrate and prove that -16 and 25 multiply to -400 and add up to 9:

-16 × 25 = -400
-16 + 25 = 9

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

x² + 9x - 400 = 0

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

(x - 16 ) (x + 25)

To summarize, since -16 and 25 multiply to -400 and add up 9, you know that the following is true:

x² + 9x - 400 = (x - 16 ) (x + 25)

Multiply To One Number and Add Up To Another
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