Question

Find the
9th term of 18b+x,19b,20b-x​

Answer 1

Answer:

d= 19b-(18b+x) = 19b-18b-x = (b-x)

an= a+ (n-1)d

a9 = 18b+x + (9-1) (b-x)

a9 = 18b +x +8b -8x = 26b -8x .

Answer 2

《¤¤¤¤¤¤¤¤¤¤¤¤¤¤》

▪Given :-

A sequence as following

18b + x , 19b , 20b - x . . .

Which is an Arithmetic Progression(A.P.)

with

First term = a = 18b +x

And

Common difference = d = b - x.

___________________________

▪To Calculate :-

9th term of the corresponding A.P.

___________________________

▪Key Concept :-

nth term of an A.P. is given by formula

$\green{ \bf a_n = a + (n - 1)d}$

___________________________

▪Solution :-

We have,

a = 18b + x

d = b - x

So,

$\sf a_9 = a + (9- 1)d \\ \\ = \sf18b + x + 8(b - x) \\ \\ = \sf18b + x + 8b - 8x \\ \\ \bf= 26b - 7x \\ \\ \large \color{magenta} \bf \underline{ \boxed{ a_9 = 26b - 7x}}$

$\mathfrak{  \text{W}hich \:   \: is  \:  \: the  \:  \: required \:  \:  \text{ A}nswer.}$

___________________________