Question

(-2)+7+(-12)+17+...+(-52)+57

Answer 1

Đặt

\(A=\left(-2\right)+7+\left(-12\right)+17+.....+\left(-52\right)+57\)

\(A=\left[\left(-2\right)+7\right]+\left[\left(-12\right)+17\right]+.....+\left[\left(-52\right)+57\right]\)

\(A=5+5+5+.....+5\)(11 cặp)

\(A=5.11=55\)

Answer 2

Ai biết giúp mk

Answer 3

\(\left(-2\right)+7+\left(-12\right)+17+.....+\left(-52\right)+\left(57\right)\)

\(\Leftrightarrow\) \(\left(\left(-2\right)+7\right)+\left(\left(-12\right)+17\right)+........\left(\left(-52\right)+57\right)\)

\(\Leftrightarrow5+5+...+5=5.6=30\)