What two numbers multiply to -21 and add up to -4?

Here we answer the question: "What two numbers multiply to -21 and add up to -4?"

The answer to your question is:

-7 and 3

Below we illustrate and prove that -7 and 3 multiply to -21 and add up to -4:

-7 × 3 = -21
-7 + 3 = -4

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

x² - 4x - 21 = 0

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

(x - 7 ) (x + 3)

To summarize, since -7 and 3 multiply to -21 and add up -4, you know that the following is true:

x² - 4x - 21 = (x - 7 ) (x + 3)

Multiply To One Number and Add Up To Another
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