1 1/3 x 1 1/4 x 1 1/5 x 1 1/6 x 1 1/7 x 1 1/8 = 4/3 x 5/4 x 6/5 x 7/6 x 8/7 x 9/8 = 4x5x6x7x8x9/3x4x5x6x7x8 = 9/3 = 3

a)2006x(2004-1004)

=2006x1000

=2006000

a)2006x(2004-1004)

 =2006x1000

 =2006000

b)=15/10+1

   =25/10

   =5/2

\(a,\dfrac{3}{2}\times\dfrac{4}{5}\times\dfrac{2}{3}\times\dfrac{15}{4}\\ =\dfrac{3\times4\times2\times15}{2\times5\times3\times4}\\ =\dfrac{3\times4\times2\times5\times3}{2\times5\times3\times4}\\ =3\)

\(b,\dfrac{6}{7}\times\dfrac{5}{8}\times\dfrac{7}{3}\times\dfrac{7}{6}\times\dfrac{8}{5}\\ =\dfrac{6\times5\times7\times7\times8}{7\times8\times3\times6\times5}\\ =\dfrac{7}{3}\)

a) \(\dfrac{3}{2}\times\dfrac{4}{5}\times\dfrac{2}{3}\times\dfrac{15}{4}\)

\(=\left(\dfrac{3}{2}\times\dfrac{2}{3}\right)\times\left(\dfrac{4}{5}\times\dfrac{15}{4}\right)\)

\(=1\times3\)

\(=3\)

b) \(\dfrac{6}{7}\times\dfrac{5}{8}\times\dfrac{7}{3}\times\dfrac{7}{6}\times\dfrac{8}{5}\)

\(=\left(\dfrac{6}{7}\times\dfrac{7}{6}\right)\times\left(\dfrac{5}{8}\times\dfrac{8}{5}\right)\times\dfrac{7}{3}\)

\(=1\times1\times\dfrac{7}{3}\)

\(=\dfrac{7}{3}\)

Chúc bạn học tốt

3/5

(8/9+3/27)x3/5

= 1 x 3/5

= 3/5

\(2\times3\times5+25\times8\times4+70+4\times2\times25\)

\(=15\times2+100\times8+70+100\times2\)

\(=30+800+70+200\)

\(=\left(30+70\right)+\left(800+200\right)\)

\(=100+100\times10\)

\(=100+1000\)

\(=1100\)

Thuận hợp lí???

1/2:2/4.3/5

=1.3/5

=3/5

\(a,1\dfrac{4}{7}.3\dfrac{4}{11}.3\dfrac{11}{15}.5\dfrac{5}{8}\)

\(=\dfrac{11}{7}.\dfrac{27}{11}.\dfrac{56}{15}.\dfrac{45}{8}\)

\(=\dfrac{11.27.56.45}{7.11.15.8}\)

\(=\dfrac{1.3.7.3}{1.1.1.1}\)

\(=63\)

\(b,\dfrac{3}{4}.1\dfrac{1}{2}+\dfrac{3}{4}.\dfrac{1}{2}\)

\(=\dfrac{3}{4}.\left(1\dfrac{1}{2}+\dfrac{1}{2}\right)\)

\(=\dfrac{3}{4}.2\)

\(=\dfrac{3}{2}\)

= 5 x ( 2+4+6+8 )

= 5 x 20 = 100

\(2.5+4.5+6.5+8.5\)

\(=\left(2+4+6+8\right).5\)

\(=20.5=100\)