What two numbers multiply to -81 and add up to 0?

Here we answer the question: "What two numbers multiply to -81 and add up to 0?"

The answer to your question is:

-9 and 9

Below we illustrate and prove that -9 and 9 multiply to -81 and add up to 0:

-9 × 9 = -81
-9 + 9 = 0

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

x² + 0x - 81 = 0

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

(x - 9 ) (x + 9)

To summarize, since -9 and 9 multiply to -81 and add up 0, you know that the following is true:

x² + 0x - 81 = (x - 9 ) (x + 9)

Multiply To One Number and Add Up To Another
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