Question 778243
16x^2-40xy+25y^2. What is the side of the square?

Area = side^2

16x^2-40xy+25y^2. 

(4x)^2-2*4*5xy+(5y)^2

(4x-5y)^2

(4x-5y)(4x-5y)

side = (4x-5y)