Question

Read the question in the picture .

Answer 1

Answer:

1st Option :

–2

Note:

★ A sequence in which the ratio between the consecutive terms are equal is called Geometric progression (GP) or geometric sequence .

★ The general term of a GP is given by ;

a(n) or T(n) = a•r^(n - 1)

★ The general form of a GP is ;

a , ar , ar² , ar³ .....

Solution:

• Given : a = 5 , T(4) = -40
• To find : common ratio , r = ?

We have ;

First term , a = 5

Also,

Fourth term , T(4) = -40

Now,

We know that ,

T(n) = a•r^(n - 1)

Thus,

=> T(4) = a•r^(4 - 1)

=> T(4) = a•r³

=> -40 = 5•r³

=> r³ = -40/5

=> r³ = -8

=> r³ = (-2)×(-2)×(-2)

=> r = [ (-2)×(-2)×(-2) ]^(1/3)

=> r = -2

Hence,

Common ratio , r = -2

Answer 2

I have attached 3 photos

Answer is option A

Hope it is helpful