1,2,4,8,16,( ) A.24 B.28 C.30 D.32 我算的是得32,但是答案上是30.很疑问啊

计算：a^2-4/3a+24÷a^3-4a/a^2+7a-8+1/3a (a+1/a)(a^2+1/a^2)(a^4+1/a^4)(a^8+1/a^8)(a^16+1/a^16)(a^32+1/a^32)(a^2-1) (4a+1)( )=16a^2+8a+1 (1-16a×a×a×a)÷（4a×a+1)÷(2a+1)² (1-16a×a×a×a)÷(4a×a+1)÷(2a+1) (a+1)(a-1)(a^2+1)(a^4+1)(a^8+1)(a^16+1)过程 (a+1)(a^2+1)(a^4+1)(a^8+1)(a^16+1)=(a-1)[(a+1)(a^2+1)(a^4+1)(a^8+1)(a^16+1)]/(a-1)=[a^2-1)(a^2+1)(a^4+1)(a^8+1)(a^16+1)]/(a-1)=[(a^4-1)(a^4+1)(a^8+1)(a^16+1)]/(a-1)=[(a^8-1)(a^8+1)(a^16+1)]/(a-1)=[(a^16-1)(a^16+1)]/(a-1)=(a^32-1)/(a-1)为什么要除 (a+1)(a-1)(a^2+1)(a^4+1)(a^8+1)(a^16+1)(a^32+1).(a^1024+1)=? (a+1)(a-1)(a^2+1)(a^4+1)(a^8+1)(a^16+1)(a^32+1).(a^1024+1)= 计算：16-a²/a²+8a+16÷a-4/2a+8；81-a²/a²+6a+9÷9-a/2a+6·1/a+9. 因式分解a^4-8a^3+24a^2-32a+16 a方+a/a方-1 8a方+16a+8/4a+4 计算[(a^2+7a-8)/(4a-a^3)]*[(a^2-4)/(3a+24)] (a^2-16)/(a^2+8a+16)÷(1-4/a) (a^2-16)/(a^2+8a+16)÷(1-4/a) 2a*a+3a+2/a+1-a*a-a-5/a+2-3a*a-4a-5/a-2+2a*a-8a+5/a-3 (a^-16)/(a^2+8a+16)÷[1-(4/a)] a^2÷[1-(4/a)]-16/(a^+8a+16)