(a^2-16)/(a^2+8a+16)÷(1-4/a)

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(a^2-16)/(a^2+8a+16)÷(1-4/a)(a^2-16)/(a^2+8a+16)÷(1-4/a)(a^2-16)/(a^2+8a+16)÷(1-4/a)(a²-16)/(a&

(a^2-16)/(a^2+8a+16)÷(1-4/a)
(a^2-16)/(a^2+8a+16)÷(1-4/a)

(a^2-16)/(a^2+8a+16)÷(1-4/a)
(a²-16)/(a²+8a+16)÷[1-(4/a)]
=(a+4)(a-4)/(a+4)²÷(a-4)/a
=(a-4)/(a+4)×a/(a-4)
=a/(a+4)

答:
此题考的是因式分解
主要难点是:
1-4/a=(a-4)/a
除以一个数,等于乘上这个数的倒数
(a²-16)/(a²+8a+16)÷[1-(4/a)]
=(a+4)(a-4)/(a+4)²÷(a-4)/a
=(a-4)/(a+4)×a/(a-4)
=a/(a+4)