Question

3,X,X+6 are in GP find the value of x ,20 the term and n th term

Answer 1

Answer:

Tn = 3(-1)^n Or,

Tn = 3(2)^n

X = -3 or 6

T20 = 1,572,864 or -3

Step-by-step explanation:

3,X,X+6 are in GP .

So, X/3 = (X+6)/X

X^2 = 3X+18

X^2 - 3X -18 = 0

X^2 + 3X - 6X -18 = 0

X(X+3) - 6(X+3) = 0

(X+3)(X-6)=0

X = -3 or 6

Terms are :

3, -3, 3 or 3,6,12

r = -1 or 2

T20 = ar^19

= 3(2)^19

= 1,572,864

Or, T20 = 3(-1)^19 = -3

Tn = 3(-1)^n Or,

Tn = 3(2)^n