Question

Factor the expression 16x²-72xy+81y²into a product of binomials

Answer 1

you know that
\[ 16x^2 -72xy +81y^2\]
is
\[(4x)^2-(2)(4)(9)xy + (9y)^2\]
so
\[ (4x+?)(4x+?) = (4x)^2-(2)(4)(9)xy + (9y)^2\]

Answer 2

4x+16
4x-16

Answer 3

you need to finish with some \[y^2\] term.
\[(4x-y)^2\] for instance would give you
\[ 16x^2 -8xy + y^2\]
so the \[16x^2\] works, how do you get a \[81y^2\]?