SOLUTION: The expression below can be rewritten in several ways. (4x-5y)(16x^2+kxy+25y^2) If this expression can be represented by (a+b)^3 where a and b are algebraic terms, what is the va

Algebra ->  Test -> SOLUTION: The expression below can be rewritten in several ways. (4x-5y)(16x^2+kxy+25y^2) If this expression can be represented by (a+b)^3 where a and b are algebraic terms, what is the va      Log On


   

Question 960758: The expression below can be rewritten in several ways.
(4x-5y)(16x^2+kxy+25y^2)
If this expression can be represented by (a+b)^3 where a and b are algebraic terms, what is the value of k?
A. -40
B. -20
C. 9
D. 40
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

%28a-b%29%5E3=%28a-b%29%28a%5E2-2ab%2Bb%5E2%29
compare to
%284x-5y%29%2816x%5E2%2Bkxy%2B25y%5E2%29
so, a=4x, b=5y and kxy=2ab=>
kxy=2%2A4x%2A5y
kxy=40xy
k=40
so, your answer is D. 40