一道初一数学题
作者:互联网
\(2^a=3\),\(3^b=2\),求 \(\dfrac1{a+1}+\dfrac1{b+1}\) 的值 .
Solve
将 \(2^a=3\) 带入 \(3^b=2\) 得 \(2^{ab}=2\),即 \(ab=1\) .
于是
\[\begin{aligned}\dfrac1{a+1}+\dfrac1{b+1}&=\dfrac{a+b+2}{ab+a+b+1}\\&=\dfrac{a+b+2}{a+b+2}\\&=1\end{aligned} \]Bonus.
构造两个无理数 \(\alpha,\beta\),令 \(\gamma = \alpha+\beta\),使得 \(\alpha\beta=\dfrac{\gamma}{\alpha\beta+\gamma+1}\) 为有理数
Solve
\(a=\log_23\),\(b=\log_32\) .
标签:ab,dfrac,一道,beta,dfrac1,初一,alpha,数学题,gamma 来源: https://www.cnblogs.com/CDOI-24374/p/16122862.html