If the 5 th term of a geometric sequence is 1875 and the $7^{\text {th }}$ term is 46875 . Find the first three terms of the sequence. [3]

Step 1 ：Given that the common ratio is \(r\), we have \(r^2 = \frac{46875}{1875} = 25 = 5^2\). Therefore, \(r = 5\).

Step 2 ：The 1st term is \(\frac{1875}{r^4} = \frac{1875}{625} = 3\).

Step 3 ：So, the first three terms are \(3, 3 \times 5 = 15, 15 \times 5 = 75\).

Step 4 ：Therefore, the first three terms of the sequence are \(\boxed{3, 15, 75}\).