Question

Tính tổng sau:

\(1+\left(-2\right)+\left(3\right)+\left(-4\right)+5+.....+\left(-98\right)+99\)

Answer 1

\(1+\left(-2\right)+3+\left(-4\right)+5+...+\left(-98\right)+99\)

\(=\left(1+3+5+...+99\right)+\left[\left(-2\right)+\left(-4\right)+...+\left(-98\right)\right]\)

\(=\frac{100.50}{2}+\frac{-100.49}{2}\)

\(=2500+\left(-2450\right)\)

\(=50\)

Answer 2

-Mơn ✖Ngáo-Picas✖ ạ ((:

Answer 3

\(1+\left(-2\right)+3+\left(-4\right)+...+\left(-98\right)+99\)

\(=\left(1+3+...+99\right)+\left[\left(-2\right)+\left(-4\right)+...+\left(-98\right)\right]\)

\(=\frac{\left(99+1\right).50}{2}+\frac{\left[\left(-98\right)+\left(-2\right)\right].50}{2}\)

\(=2550+\left(-2450\right)=50\)