Question 28228
Find a value for k so that 9m^2-kn^2 will have the factors 3m+7n and 3m-7n.

 (3m+7n)*(3m-7n)= (3M)^2- (7N)^2 = 9M^2-49N^2
COMPARING WITH 9m^2-kn^2...WE GET K=49