数学课前练习

1. 已知等比数列\(\{a_n\}\)满足\(a_1 = 3\)，\(a_1 + a_3 + a_5 = 21\)，则\(a_3 + a_5 + a_7 = \ )

A. 21

B. 42

C. 63

D. 84

2. 将4个1和2个0随机排成一行，则2个0不相邻的概率为(\ )

A. \(\displaystyle \frac{1}{3}\)

B. \(\displaystyle \frac{2}{5}\)

C. \(\displaystyle \frac{2}{3}\)

D. \(\displaystyle \frac{4}{5}\)