What two numbers multiply to 648 and add up to 81?

Here we answer the question: "What two numbers multiply to 648 and add up to 81?"

The answer to your question is:

9 and 72

Below we illustrate and prove that 9 and 72 multiply to 648 and add up to 81:

9 × 72 = 648
9 + 72 = 81

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

x² + 81x + 648 = 0

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

(x + 9 ) (x + 72)

To summarize, since 9 and 72 multiply to 648 and add up 81, you know that the following is true:

x² + 81x + 648 = (x + 9 ) (x + 72)

Multiply To One Number and Add Up To Another
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