Question

= (10xi) -এর মান হলাে
(a) 550
| (c) 450
(b) 650
(d) 300​

Answer 1

Solution

=10×1+10×2+10×3+......+10×10

=10(1+2+3+4+.....+10)

$= 10 \times \frac{10(2 \times 1 + (10 - 1)1)}{2} \\ = 10 \times \frac{10 \times 11}{2} \\ = 10 \times 55 \\ = 550$