a) 270

 b)600

 c)9000

  d)770

a) 15.18 = 3.5.3.6= 3².5.6= 9.30 = 270

b) 25.24= 25.4.6= 100.6 = 600

c) 125.72= 5.5².4.18 = 5.100.18= 1800.5=9000   

d) 55.14= 5.11.7.2 = 5.2.11.7= 10.11.7= 110.7= 770

a) 15.18

=3.5.3.6

= (3.3).(5.6)

=9.30

=270

b) 25.24

=5.5.2.12

=(5.2).(5.12)

=10.60

=600

c)125.72

=25.5.8.9

=(25.8).(5.9)

=200.45

=9000

d)55.14

=5.11.2.7

=(5.2).(11.7)

=10.77

=770.Hok tốt~

270

600

9000

770

theo thứ tự r đó

a) 15.18

=3.5.3.6

=9.30

=270

b) 25.24

=5.5.2.2.6

=10.10.6

=600

= 25.24 + 2.25.83

= 25(24 + 2.83)

= 25.190 = 4750

\(=25\cdot\left(76+24\right)+75\left(147-47\right)\)

=10000

25. (76+24) + 75.(147-47)

= 25. 100 +75. 100

= 10000

25.76 + 75.147 + 25.24 - 47.75
=[ 25 . ( 76 + 24 )] + [75 . ( 147 – 47 ) ]
= [ 25 . 100 ] + [ 75 . 100 ]
= 2500 + 7500
= 10 000

125.72=125.(70+2)=125.70+125.2=8750+250=9000

C = \(\frac{6}{15.18}+\frac{6}{18.21}+...+\frac{6}{87.90}\)

C = \(2.\left(\frac{1}{15}-\frac{1}{18}+\frac{1}{18}-\frac{1}{21}+...+\frac{1}{87}-\frac{1}{90}\right)\)

C = \(2.\left(\frac{1}{15}-\frac{1}{90}\right)=2.\frac{1}{18}\)

C = \(\frac{1}{9}\)

\(B=\frac{6}{1.3}+\frac{6}{3.5}+\frac{6}{5.7}+\frac{6}{7.9}+...+\frac{6}{99.101}\)

\(=3.\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+....+\frac{9}{99.101}\right)\)

\(=3.\left(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+....+\frac{1}{99}-\frac{1}{101}\right)\)

\(=3.\left(\frac{1}{1}-\frac{1}{101}\right)=3.\left(\frac{101}{101}-\frac{1}{101}\right)=3.\frac{100}{101}=\frac{300}{101}\)

\(C=\frac{6}{15.18}+\frac{6}{18.21}+\frac{6}{21.24}+...+\frac{6}{87.90}\)

\(=2.\left(\frac{3}{15.18}+\frac{3}{18.21}+\frac{3}{21.24}+...+\frac{3}{87.90}\right)\)

\(=2.\left(\frac{1}{15}-\frac{1}{18}+\frac{1}{18}-\frac{1}{21}+\frac{1}{21}-\frac{1}{24}+....+\frac{1}{87}-\frac{1}{90}\right)\)

\(=2.\left(\frac{1}{15}-\frac{1}{90}\right)=2.\left(\frac{6}{90}-\frac{1}{90}\right)=2.\frac{5}{90}=\frac{1}{9}\)