C-13-Q053mediumsingle_mcq

The sum of the first $9$ terms of $8 + 16 + 24 + \cdots$ is —

Here $a=8$ , $d=8$ , $n=9$ , so $S = \frac{9}{2} {2 (8) + (9 - 1$ .

53/160

এই অধ্যায়ের আরও প্রশ্ন

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432

)

(

8

)

}

=

\frac{9}{2}

(

16

+

64

)

=

\frac{9}{2}

\cdot

80

=

360

S=\dfrac{9}{2}\{2(8)+(9-1)(8)\}=\dfrac{9}{2}(16+64)=\dfrac{9}{2}\cdot 80=360

S = \frac{9}{2} {2 (8) + (9 - 1) (8)} = \frac{9}{2} (16 + 64) = \frac{9}{2} \cdot 80 = 360