SOLUTION: This is confusing me...can someone explain this to me? FIND A VALUE FOR k SO THAT 9m^2 - kn^2 WILL HAVE THE FACTORS 3m + 7n AND 3m -7n

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: This is confusing me...can someone explain this to me? FIND A VALUE FOR k SO THAT 9m^2 - kn^2 WILL HAVE THE FACTORS 3m + 7n AND 3m -7n      Log On


   

Question 44882: This is confusing me...can someone explain this to me?
FIND A VALUE FOR k SO THAT 9m^2 - kn^2 WILL HAVE THE FACTORS 3m + 7n AND 3m -7n
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
If the factors are %283m+%2B+7n%29 and 3m+-+7n%29
multiply out the factors to get the solution
%283m+%2B+7n%29%283m+-+7n%29+=+9m%5E2+-+49n%5E2
9m%5E2+-+kn%5E2+=+9m%5E2+-+49n%5E2
subtract 9m%5E2 from both sides
-+kn%5E2+=+-49n%5E2
divide both sides by -n%5E2
k+=+49 answer