Answer
$1 ± \sqrt 5$
Work Step by Step
The trinomial cannot be factored so we use the quadratic formula to calculate the x.
$x= \frac{-b ± \sqrt (b^{2} - 4ac)}{2a}$
$n^{2} - 2n - 4$
In this trinomial a = 1, b= -2 and c= -4
$x= \frac{-(-2) ± \sqrt (-2^{2} - 4(1)(-4))}{2(1)}$
$x= \frac{2 ± \sqrt (4 + 16)}{2}$
We add the 4 and 16 together
$x= \frac{2 ± \sqrt (20)}{2}$
Square root of 20 is $2\sqrt 5$ because the factors of 72 are 4 and 5 and 4 is a perfect square of 2.
$x= \frac{2 ± 2\sqrt 5}{2}$
We simplify the numbers to get the final x value.
$n= 1 ± \sqrt 5$
