Find the sum of the series up to $90$ terms:
$1 + 2 + 3 + 3 + 4 + 6 + 5 + 6 + 9 +$ ....

1613

No worries! We‘ve got your back. Try BYJU‘S free classes today!

3225

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

6450

No worries! We‘ve got your back. Try BYJU‘S free classes today!

9675

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is C $3225$
Series $= (1 + 2 + 3) + (3 + 4 + 6) + (5 + 6 + 9) + . . . . .$
$= 6 + 13 + 20 + . . . . (30 t e r m s)$
Here, $d = 7, a = 6, n = 30$
As we know, $S_{n} = \frac{n}{2} [2 a + (n - 1) d]$
$∴ S_{30} = \frac{30}{2} [12 + (29) (7)] = 3225$

Suggest Corrections

Similar questions

1 + 6 + \frac{9 (1^{2} + 2^{2} + 3^{2})}{7} + \frac{12 (1^{2} + 2^{2} + 3^{2} + 4^{2})}{9} + \frac{15 (1^{2} + 2^{2} + . . . . + 5^{2})}{11} + . . . . .

15

(3^{3} - 2^{3}) + (5^{3} - 4^{3}) + (7^{3} - 6^{3}) + . . . . . .

10

9

\frac{1}{2} + \frac{1}{3} + \frac{1}{6} + . . .

n

1 \times 2 \times 3 + 2 \times 3 \times 4 + 3 \times 4 \times 5 + . . . . . . . . . . . .

The sum to 2n terms of the series - $5^{3} + 4 \times 6^{3} + 7^{3} + 4 \times 8^{3} + 9^{3}$ ....is?

Join BYJU'S Learning Program