f.4 maths

1.
(4a/b)^3(-b^2/a)^2

= (64a^3 / b^2) ( b^4 / a^2)

= 64a/b^2


2.
(a^2m．am+1)^2．am

= [ a^2m x a^(m + 1) ]^2 (a^m)

= (a^3m + 1)^2 (a^m)

= (a^6m + 2) (a^m)

= a^(7m + 2)


3.
xn-1y^2n/xn+1(y^2)n-1

= x^(n - 1) y^2n / x^(n + 1) (y^2n - 2)

= x^(n - 1 - n - 1) y^(2n - 2n + 2)

= y^2/x^2


4.
3n+1+3n/2*3n

= 3^(n + 1) + 3^n / 2(3^n)

= 3^n (3 + 1) / 2(3^n)

= 2


P.S a^b 係代表a ge b次方