Question

determinati opusul numerelor. a=5+7+9.......+81

Answer 1

$a = 5 + 7 + 9 + ... + 81$

$r = 2$

$a = \frac{81 - 5}{2} + 1 = \frac{76}{2} + 1 = 38 + 1 = 39$

$-a=-39$