Answer:
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
