What two numbers multiply to 399 and add up to -64?

Here we answer the question: "What two numbers multiply to 399 and add up to -64?"

The answer to your question is:

-57 and -7

Below we illustrate and prove that -57 and -7 multiply to 399 and add up to -64:

-57 × -7 = 399
-57 + -7 = -64

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

x² - 64x + 399 = 0

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

(x - 57 ) (x - 7)

To summarize, since -57 and -7 multiply to 399 and add up -64, you know that the following is true:

x² - 64x + 399 = (x - 57 ) (x - 7)

Multiply To One Number and Add Up To Another
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