Question

Tính nhanh :

1+(-4)+2+(-5)+3+(-6).....+17+(-20) 

Answer 1

Answer 2

Answer 3

Ta có:

1+(-4)+2+(-5)+3+(-6)+...+17+(-20)

= 1-4+2-5+3-6+...+17-20

= -3-3-3-...-3

= 17(-3)

= -51

Answer 4

Ta có: \(1+\left(-4\right)+2+\left(-5\right)+3+\left(-6\right)+...+17+\left(-20\right)\)

\(=\left(-3\right)\cdot17=-51\)