4,5*1,5+4,5*4,5+3*4,5

=4,5*\((\)1,5+4,5\()\)+3*4,5

=4,5*6+3*4,5

=4,5*\((\)6+3\()\)

=4,5*9

=40,5

\(\frac{1}{2}\times\frac{3}{15}+\frac{13}{15}\times\frac{1}{2}-\frac{1}{2}\times\frac{1}{15}\)

\(=\frac{1}{2}\times\left(\frac{3}{15}+\frac{13}{15}-\frac{1}{15}\right)\)

\(=\frac{1}{2}\times1=\frac{1}{2}\)

~ Hok tốt ~

1/2 . 3/15 + 13/15 . 1/2 - 1/2 . 1/15

= 1/2 . ( 3/15 + 13/15 - 1/15 )

= 1/2 . 15/15

= 1/2 . 1

= 1/2

                            #Louis

\(\frac{1}{2}\times\frac{3}{15}+\frac{13}{15}\times\frac{1}{2}-\frac{1}{2}\times\frac{1}{15}\)

\(=\frac{1}{2}\times\left(\frac{3}{15}+\frac{13}{15}-\frac{1}{15}\right)\)

\(=\frac{1}{2}\times1\)

\(=\frac{1}{2}\)

Study well ! >_<

\(\dfrac{7}{5}\times\dfrac{11}{24}\times\dfrac{5}{7}\times\dfrac{24}{55}\\ =\left(\dfrac{7}{5}\times\dfrac{5}{7}\right)\times\left(\dfrac{11}{24}\times\dfrac{24}{55}\right)\\ =1\times\dfrac{1}{5}\\ =\dfrac{1}{5}\)

\(\dfrac{7x11x5x24}{5x24x7x55}\)=\(\dfrac{11}{55}\)=\(\dfrac{1}{5}\)

= (7/5 x 5/7) x (11/24 x 24/55)

= 1 x 1/5

= 1/5

5 giờ 15 phút x 2 + 4 giờ 45 phút x 2 

= ( 5 giờ 15 phút + 4 giờ 45 phút ) x 2

= 10 giờ x 2

= 20 giờ

=( 5 giờ 15 phút + 4 giờ 45 phút ) x 2

= 9 giờ 60 phút x 2

= 20 giờ

a) 4 x 9120 x 25

= 25 x 4 x 9120

= 100 x 9120

= 912000

b) 15 800 + 4 200 + 7 260 + 2 740

= (15800 + 4200) + (7260 + 2740)

= 20000 + 10000

= 30000

a) 4 x 9120 x 25

= 25 x 4 x 9120

= 100 x 9120

= 912000

b) 15 800 + 4 200 + 7 260 + 2 740

= (15800 + 4200) + (7260 + 2740)

= 20000 + 10000

= 30000

\(50\times45\times2\)

\(=100\times45\)

\(=4500\)

\(78\times2\times5\)

\(=78\times10\)

\(=780\)

50 x 45 x 2 

= 45 x ( 50 x 2 )

= 45 x 100 = 4500

78 x 2 x 5

= 78 x ( 2 x 5 )

= 78 x 10 = 780

\(\frac{14}{9}:\frac{13}{12}+\frac{4}{3}:\frac{13}{12}\)

\(=\frac{14}{9}\cdot\frac{12}{13}+\frac{4}{3}\cdot\frac{12}{13}\)

\(=\left(\frac{14}{9}+\frac{4}{3}\right)\cdot\frac{12}{13}\)

\(=\frac{26}{9}\cdot\frac{12}{13}=\frac{8}{3}\)

=5/13x(4/5-9/15)

=5/13x1/5

=1/13

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