Question

Calculați:
a)|+5|+|-9|-|-3|+|+8|=?
b)1-2+3-4+5-6+.....+101-102=?

plzz.

Answer 1

$a)\quad |+5|+|-9|-|-3|+|+8|=\\ \\ =(5)+(9)-(3)+(8) = \\ \\ = 5+9-3+8 = 14+5 = 19$

$b)\quad 1-2+3-4+5-6+...+101-102= \\ \\ = -1-1-1- \underset{\text{de 56 ori}}{\underbrace{...}} - 1 = -56$