Cho P = (2x - x^2/2x^2 + 8 - 2x^2/x^3 - 2x^2 + 4x - 8).(2/x^2 + 1 - x/x)

Cho P= (2x-x^2/2x^2+8 - 2x^2/x^3-2x^2+4x-8) . (2/x^2 + 1-x/x)
a) rút gọn P
b) tìm x để P=4
c) tìm Min M= P . 2x.(x+3)