на фото..............
1) 8/3 x^2y^8 *(-3/2 xy^3)^4 = 8/3 x^2y^8 * 81/4 x^4y^12 = 54 x^6y^20.
2) x^(n-2)*x^(3-n)*x= x^(n-2+3-n+1) = x^2