Here we answer the question: "What two numbers multiply to -81 and add up to 80?"
The answer to your question is:
-1 and 81
Below we illustrate and prove that -1 and 81 multiply to -81 and add up to 80:
-1 × 81 = -81
-1 + 81 = 80
Are you asking because you are trying to figure out how to factor the following quadratic equation?
x2 + 80x - 81 = 0
If so, the solution to factor the quadratic equation above is:
(x - 1 ) (x + 81)
To summarize, since -1 and 81 multiply to -81 and add up 80, you know that the following is true:
x2 + 80x - 81 = (x - 1 ) (x + 81)
Multiply To One Number and Add Up To Another
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