Answer
$16x^2y^4-8x^2y^3+x^2y^2$
Work Step by Step
The square of a binomial sum is: $(A+B)^2=A^2+2AB+B^2$.
The square of a binomial difference is: $(A-B)^2=A^2-2AB+B^2$.
Hence here: $(4xy^2-xy)^2=(4xy^2)^2-2\cdot4xy^2\cdot xy+(xy)^2=16x^2y^4-8x^2y^3+x^2y^2$