Question

R=1+2-3+4-5+...+98-99+100

Answer 1

\(R=1+2-3+4-5+...+98-99+100\) 

= \((-1+2)+(-3+4)+(-5+6)+...+(-99+100)\) 

= \(1+1+1+...+1\) 

=> (có \(\dfrac{100}{2}=50\) số 1) <=> \(1.50=50\)

Answer 2

R = (1 + 2) + (-3 + 4) + (-5 + 6) + ... + (-99 + 100)

= 3 + 1 + 1 + ... + 1 (49 chữ số 1)

= 3 + 49

= 52