What two numbers multiply to -9 and add up to 8?

Here we answer the question: "What two numbers multiply to -9 and add up to 8?"

The answer to your question is:

-1 and 9

Below we illustrate and prove that -1 and 9 multiply to -9 and add up to 8:

-1 × 9 = -9
-1 + 9 = 8

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

x² + 8x - 9 = 0

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

(x - 1 ) (x + 9)

To summarize, since -1 and 9 multiply to -9 and add up 8, you know that the following is true:

x² + 8x - 9 = (x - 1 ) (x + 9)

Multiply To One Number and Add Up To Another
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