Ineed to do this problem by completing the square .

the roots are n = 1 + √15 and n = 1 - √15

Step-by-step explanation:

In this case I would immediately rewrite n² - 2n - 5 = 10 as

n² - 2n                  = 10 + 5 = 15.

To complete the square:  Identify the coefficient of n (it is -2). Halve that, obtaining -1, square this result, and then add the outcome (1) to and subtract the outcome (1) to n² - 2n:

n² - 2n  + 1 - 1               = 15

Next, rewrite n² - 2n  + 1 as the square of a binomial:

(n - 1)² = 15

Finally, take the square root of both sides:

n - 1 = ±√15

so that the roots are n = 1 + √15 and n = 1 - √15

m a t h w a y. c o m

step-by-step explanation: