电子课本网 第41页

第41页

信息发布者:
$(a + b)(a - b)$
$(a + b)(a - b)=a^{2}-b^{2}$
解:
​$\begin {aligned}&2×(1+\frac {1}{2})×(1+\frac {1}{2^2})×(1+\frac {1}{2^4})×(1+\frac {1}{2^8})+\frac {1}{2^{14}}\\=&4×(1-\frac {1}{2})×(1+\frac {1}{2})×(1+\frac {1}{2^2})×(1+\frac {1}{2^4})×(1+\frac {1}{2^8})+\frac {1}{2^{14}}\\=&4×(1-\frac {1}{2^2})×(1+\frac {1}{2^2})×(1+\frac {1}{2^4})×(1+\frac {1}{2^8})+\frac {1}{2^{14}}\\=&4×(1-\frac {1}{2^4})×(1+\frac {1}{2^4})×(1+\frac {1}{2^8})+\frac {1}{2^{14}}\\=&4×(1-\frac {1}{2^8})×(1+\frac {1}{2^8})+\frac {1}{2^{14}}\\=&4×(1-\frac {1}{2^{16}})+\frac {1}{2^{14}}\\=&4-\frac {1}{2^{14}}+\frac {1}{2^{14}}\\=&4\end {aligned}$​
$(a + b)^{3}=a^{3}+b^{3}+3a^{2}b + 3ab^{2}$
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​$(x + 1)(x - 1)x=x^3-x$​