Here we answer the question: "What two numbers multiply to 990 and add up to -81?"
The answer to your question is:
-66 and -15
Below we illustrate and prove that -66 and -15 multiply to 990 and add up to -81:
-66 × -15 = 990
-66 + -15 = -81
Are you asking because you are trying to figure out how to factor the following quadratic equation?
x2 - 81x + 990 = 0
If so, the solution to factor the quadratic equation above is:
(x - 66 ) (x - 15)
To summarize, since -66 and -15 multiply to 990 and add up -81, you know that the following is true:
x2 - 81x + 990 = (x - 66 ) (x - 15)
Multiply To One Number and Add Up To Another
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