SOLUTION: Which value of k makes the following equation an identity: 16n to the 4th power - 9 = (4n + k)(4n - k) a. k = 3 b. k = 9 c. k = 4 d. k = 5 I don't know how to figure th

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Which value of k makes the following equation an identity: 16n to the 4th power - 9 = (4n + k)(4n - k) a. k = 3 b. k = 9 c. k = 4 d. k = 5 I don't know how to figure th      Log On


   

Question 870567: Which value of k makes the following equation an identity: 16n to the 4th power - 9 = (4n + k)(4n - k)
a. k = 3
b. k = 9
c. k = 4
d. k = 5
I don't know how to figure this out because I don't understand what an identity is.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
16n^2-(k)^2=(4n+k)(4n-k)
16n^2-9
(4n)^2-(3)^2
(4n+3)(4n-3)
compare the factors
so k=3