Question

sum up the series

3+4+7+8+11+12+15+16+....to 20 terms​

Answer 1

Answer:

Rearrange the terms

(3 + 7 + 11 + ....10 terms) + (4 + 8 + 12 + .....10 terms)

$\frac{10}{2} (2 \times 3 + 9 \times 4) + \frac{10}{2} (2 \times 4 + 9 \times 4) \\ = 5 \times 42 + 5 \times 44 \\ = 210 + 220 \\ = 430$

Answer 2

Answer:

this is correct..........................