Angle sums properties iready

help i’m unsure!

9514 1404 393

  D: 21

Step-by-step explanation:

The first term is (a1). The third term is (a1)r². The product of these terms is ...

  (a1)(a1)r² = ((a1)r)², the square of the second term.

The missing term is √(7·63) = √441 = 21.

Additional comment

In consideration of the above, you can also see that the common ratio can be found from ...

  a3/a1 = ((a1)r²)/(a1) = r² = 63/7 = 9

Then the common ratio is r = √9 = 3, and the second term is 7·3 = 21.