What two numbers multiply to -640 and add up to -123?

Here we answer the question: "What two numbers multiply to -640 and add up to -123?"

The answer to your question is:

-128 and 5

Below we illustrate and prove that -128 and 5 multiply to -640 and add up to -123:

-128 × 5 = -640
-128 + 5 = -123

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

x² - 123x - 640 = 0

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

(x - 128 ) (x + 5)

To summarize, since -128 and 5 multiply to -640 and add up -123, you know that the following is true:

x² - 123x - 640 = (x - 128 ) (x + 5)

Multiply To One Number and Add Up To Another
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