Here we answer the question: "What two numbers multiply to -399 and add up to -2?"
The answer to your question is:
-21 and 19
Below we illustrate and prove that -21 and 19 multiply to -399 and add up to -2:
-21 × 19 = -399
-21 + 19 = -2
Are you asking because you are trying to figure out how to factor the following quadratic equation?
x2 - 2x - 399 = 0
If so, the solution to factor the quadratic equation above is:
(x - 21 ) (x + 19)
To summarize, since -21 and 19 multiply to -399 and add up -2, you know that the following is true:
x2 - 2x - 399 = (x - 21 ) (x + 19)
Multiply To One Number and Add Up To Another
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