Question

if 9th term of Ap is zero than so that 29th term is double of 19th term​

Answer 1

Step-by-step explanation:

Let the first term of an A.P. = a

And common difference = d

Given: 9th term of an A.P. is 0. Therefore,

We have to prove that

Thus,

And

From equation (2) and (3),

Hence proved

Answer 2

$\huge \underline\mathfrak \red{ANSWER : } \over$

Let the first term of an A.P = a

And common difference = d

Given : 9th term of an A.P. is 0

Therefore,

a + (9 - 1)d = 0

a + 8d = 0 ........(1)

We have to prove that, T19 = 2T9

Thus,

T19 = a + (19 - 1) d

= 8a + 18d .........(a = 8d from eqn 1)

=10d .........(2)

And,

T29=a+(29-1)d

=a+28d

= -8d + 28d ........(a = 8d from eqn 1)

= 20d .........(3)

From equation (2) and (3),

$\boxed{T19 = 2T29}$

Hence proved.