What two numbers multiply to 399 and add up to 400?

Here we answer the question: "What two numbers multiply to 399 and add up to 400?"

The answer to your question is:

1 and 399

Below we illustrate and prove that 1 and 399 multiply to 399 and add up to 400:

1 × 399 = 399
1 + 399 = 400

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

x² + 400x + 399 = 0

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

(x + 1 ) (x + 399)

To summarize, since 1 and 399 multiply to 399 and add up 400, you know that the following is true:

x² + 400x + 399 = (x + 1 ) (x + 399)

Multiply To One Number and Add Up To Another
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