Question

câu 1:1+2+3+...+2012+2013

câu 2: 12:{390:[500(125+35.7)

câu 3:(15+x):3 bằng 3^6:3^3

Answer 1

\(\frac{15+x}{3}=\frac{3^6}{3^3}\)

\(\Leftrightarrow\)\(\frac{15+x}{3}=3^3\)

\(\Leftrightarrow15+x=3^4\)

\(\Leftrightarrow x=81-15=66\)

Answer 2

\(\left(15+x\right):3=3^6:3^3\)

\(\left(15+x\right):3=27\)

\(15+x=27.3\)

\(15+x=81\)

\(x=81-15\)

\(x=66\)

vậy x=66

Answer 3

\(1+2+3+4+...+2012+2013\)

\(=\frac{2013.\left(2013+1\right)}{2}\)

\(=2027091\)