不大于 $\dfrac{3^{100}+2^{100}}{3^{96}+2^{96}}$ 的最大整数为_______.
答案 $80$.
解析 根据题意,有\[\dfrac{3^{100}+2^{100}}{3^{96}+2^{96}}=\dfrac{3^4+\left(\dfrac 23\right)^{96}\cdot 2^4}{1+\left(\dfrac 23\right)^{96}}<3^4,\]而\[\dfrac{3^4+\left(\dfrac 23\right)^{96}\cdot 2^4}{1+\left(\dfrac 23\right)^{96}}>3^4-1\Longleftarrow \left(\dfrac 23\right)^{96}<\dfrac 1{64}\Longleftarrow \left(\dfrac 23\right)^{16}<\dfrac 12,\]事实上 $\left(\dfrac 23\right)^{16}=\left(\dfrac 49\right)^8<\dfrac 1{2^8}$,不等式成立. 综上所述,所求整数为 $80$.