p(x,y)=1800x^.621*y^.379

a.) find number of units produced with x labor and y unity of capital

answer: i got 3888064

b. marginal productivies

answer i got: Px = -4749x^-.379*y^.379

Py = -118x^.621*y^-.621

c.) estimate productiives at x=2500 and y 1700

i got: Px=-4103

Py=-1421

I am NOT sure if i did everything correct and if i did something wrong, can someone help me???