Question

Tính hợp lí :

a, 102-96+90-84+78-72+66-60=54-48

B, (2+4+6+...+2006)-(1+3+5+...+2005)

Answer 1

a) \(102-96+90-84+78-72+66-60+54-48\)

\(=\left(102-96\right)+\left(90-84\right)+\left(78-72\right)+\left(66-60\right)+\left(54-48\right)\)

\(=6+6+6+6+6\)

\(=30\)

b) \(\left(2+4+6+...+2006\right)-\left(1+3+5+...+2005\right)\)

\(=\left(2-1\right)+\left(4-3\right)+\left(6-5\right)+...+\left(2006-2005\right)\)

\(=1+1+1+...+1\) (1003 chữ số 1)

\(=1.1003\)

\(=1003\)