Question

Bài 1: Không quy đồng hãy tính hợp lý.

a) A=\(\frac{-1}{20}\)+ \(\frac{-1}{30}\)+ \(\frac{-1}{42}\)+ \(\frac{-1}{56}\)+ \(\frac{-1}{72}\)+ \(\frac{-1}{90}\)

b) B=\(\frac{5}{2.1}\)+ \(\frac{4}{1.11}\)+ \(\frac{3}{11.2}\)+ \(\frac{1}{2.15}\)+ \(\frac{13}{15.4}\)

Bài 2: Không tính giá trị hãy so sánh.

a) \(\frac{1717}{8585}\)và \(\frac{1313}{5151}\)                             b)\(\frac{201201}{202202}\)và \(\frac{201201201}{202202202}\)

 

 

Answer 1

Bài 1 :

a) \(A=\frac{-1}{4.5}+\frac{-1}{5.6}-\frac{-1}{7.8}+\frac{-1}{9.10}\)

\(A=\frac{1}{4}\)\(-\left(-\frac{1}{5}\right)+...+\left(-\frac{1}{9}\right)-\left(-\frac{1}{10}\right)\)

\(A=\frac{1}{4}+\frac{1}{10}\)

\(A=\frac{3}{20}\)

Answer 2

Bài 2:

a,17178585=1717:17178585:1717=15;13135151=1313:1015151:101=135115=51255<65255=1351⇒17178585<13135151a,17178585=1717:17178585:1717=15;13135151=1313:1015151:101=135115=51255<65255=1351⇒17178585<13135151

b,201201202202=201201:1001202202:1001=201202=201⋅1001001202⋅1001001=201201201202202202