Answer:
C. 4x+5y
Explanation:
Lets start by factorizing the expression 16x²+40xy+25y²
Consider the expression ax²+bx+c
During factorization, two numbers picked should add up to b while the product should be=ac
We find two numbers that when added give 40 and when multiplied = 16×25=400
These numbers are 20 and 20
Therefore the expression will be broken into:
16x²+20xy+20xy+25y²
4x(4x+5y)+5y(4x+5y)
(4x+5y)(4x+5y)
The expression is a perfect square.