Answer:
189, -567, 1701
Step-by-step explanation:
this is a geometric sequence so we can find out what is done to each number to get the next one by taking for example 21 and dividing by -7. this gives us -3. we can check this again by dividing -63 by 21. we get the same answer, -3. so to find the next number in the sequence we multiply each number by -3 which gives us the numbers, -7, 21, -63, 189, -567, 1701
