Search
Ask a question
0

A sequence has a common ratio

A sequence has a common ratio of R=-2 so if G3=7 what is G5
 
A. 3 
B. -14 
C. 28 
D. -28

Comments

G3(-2)(-2) = G5
4G3 = G5
4(7) = G5
28 = G5

2 Answers by Expert Tutors

Tutors, sign in to answer this question.
Andy C. | Math/Physics TutorMath/Physics Tutor
5.0 5.0 (14 lesson ratings) (14)
1
C(-2^0) = C  <---G1
 
C(-2^1) = -2C <--- G2
 
C(-2)^3 = 7 <--- G3
 
-8C = 7
 
C = -7/8
 
So G5 = (-7/8)(-2)^4 = (-7/8)(16) = -14
 
G(n) = (-7/8)(-2)^(n-1)
 
Answer : B
Mark M. | Math Tutor--High School/College levelsMath Tutor--High School/College levels
4.9 4.9 (809 lesson ratings) (809)
0
Gn = G1rn-1
 
G3 = G1(-2)2 = 7
 
So, G1 = 7/4
 
G5 = G1r4 = (7/4)(-2)= 28
 
Answer:  C