本团长来帮你
x·(9x^3y-3xy^2)÷(-3x^2y)
=(9x^4y-3x^2y^2)÷(-3x^2y)
=-3x²+y
[(x+y)^2-(x-y)^2]÷(-4xy)
=(x²+2xy+y²-x²+2xy-y²)÷(-4xy)
=4xy÷(-4xy)
=-1