What is the sum of the geometric sequence 1, 4, 16, if there are 8 terms?
21,845
43,690
65,535
87,380

The sum of geometric sequence:

S n = a 1 * ( q^n - 1 ) / ( q - 1 )

where:  a 1 = 1,

q = a 2 : a 1 = 4 : 1 = 4

S 8 = 1 * ( 4^(8) - 1 ) / ( 4 - 1 ) =

= ( 65,536 - 1 ) / ( 4 - 1 ) = 65,535 / 3 = 21,845

answer

a,b, and d

explanation

a reflection angle is more than

but less than;

an angle that measures

is a reflex angle.(true)

an angle that measures less than

is acute.(true)

provided we are considering angles greater or equal to zero.

an acute angle lies in the range.

an obtuse angle is less than 180° but more than 90°

an angle that measures 300° is obtuse (false)

an angle that measures 65° is an acute angle.(true)