Question

How do you factor `5n^2-4n-1`?

Answer 1

`(5n + 1)(n - 1)`

Answer 2

(5n + 1)(n - 1)

Explanation:

Use the new AC Method (Socratic, Google Search)
`y = 5n^2 - 4n - 1`
Converted trinomial:
`y' = n^2 - 4n - 5`.
Method. Find the 2 factor numbers of y', then, divide them by a.
Find 2 numbers, that have opposite signs (ac < 0), knowing their sum (b = -4) and their product (ac = - 5). They are 1 and - 5.
Back to y, the factor-numbers are:
`n1 = 1/a = 1/5` and `n2 = -5/5 = -1`
Factored form:
`y = 5(n + 1/5)(n - 1) = (5n + 1)(n - 1)`