Question

Mọi người giúp em với:
Tính nhanh:
a) 1+2-3-4+5+6-7-8+9+10-11-12+......-299-300+301+302

b) 2-2/19+2/43-2/1943                            4-4/29+4/41-4/2941

----------------------------------       :        -------------------------------------

   3-3/19+3/43-3/1943                             5-5/29+5/41-5/2941

 

 

 

Answer 1

b. \(\frac{2-\frac{2}{19}+\frac{2}{43}-\frac{2}{1943}}{3-\frac{3}{19}+\frac{3}{43}-\frac{3}{1943}}:\frac{4-\frac{4}{29}+\frac{4}{41}-\frac{4}{2941}}{5-\frac{5}{29}+\frac{5}{41}-\frac{5}{2941}}=\frac{2}{3}:\frac{4}{5}=\frac{5}{6}\)

Answer 2

a) 1+2-3-4+...-299-300+301+302

= (1+2-3) + (-4+5+6-7) +...+ (298-299-300+301) +302

= 0+ 0 + 0 +...+ 0 + 302

= 302