指數問題!!!

16(a) =(x^2/y^6)(x/x^3y^2)
= (x^(2+1-3)/y^(6+2)
=x^0/y^8
=1/y^8

(b) =(x^6/y^8) * (y^2/x^4)
=x^(6-4)y^(-8+2)
=x^2y^(-6)
=x^2/y^6

(c) =(16x^2/9y^4) ÷ (8x^9/y^9)
=(16x^2/9y^4) * (y^9/8x^9)
=2x^(2-9)y^(9-4) / 9
=2x^(-7)y^5/9
=(2y^5)/(9x^7)

18(a) =2^(2n+2)/2^(2n+1)
=2^(2n+2-2n-1)
=2^1
=2

(b) =3x5^(n+3)/(5x5^n)
=3x5^(n+3-n-1)
=3x5^2
=3x25
=75

(c) =5x2^(n+1)/2^(2n+2)
=5x2^(n+1-2n-2)
=5x2^(-n-1)
=5/2^(n+1)

As follows~~~


圖片參考：http://i182.photobucket.com/albums/x4/A_Hepburn_1990/index4.jpg?t=1189235800