find the sum for each geometric sequence a1=15,r=2,n=4
The sum of a geometric sequence can be found using the formula:
Sn = a1(1 - r^n) / (1 - r)
Plugging in the values given:
S4 = 15(1 - 2^4) / (1 - 2)
S4 = 15(-15) / (-1)
S4 = 225
Therefore, the sum of the geometric sequence with a1=15, r=2, and n=4 is 225.