1. Mẫu số chung là 3x4x5=60

1/3 = 1x4x5/60 = 20/60

2/4 = 2x3x5 = 30/60

4/5 = 4x3x4 = 48/60

2. Tính nhanh 35x26+35x27+70/(35+35+...+35)

= 35x(26+27)+35x2/35x100

=35x53+1/50

=(35x53x50+1)/50

= 92751/50

\(=\dfrac{35\left(26+72+2\right)}{35\cdot100}=1\)

\(\dfrac{35.26+35.72+70}{35+35+...+35}\)(100 số 35 ở mẫu)

=\(\dfrac{35.26+35.72+35.2}{35.100}\)

=\(\dfrac{35.\left(26+72+2\right)}{35.100}\)

=\(\dfrac{35.100}{35.100}\)

=1

a)      29 + 132 + 237 + 868 + 763

    =  ( 132 + 868 ) + ( 237 + 763 ) + 29

    = 1000 + 1000 + 29

    =  1000 x 2 + 29

    =  2000 + 29

    =  2029

b)    35 x 34 + 35 x 38 + 65 x 75 + 45

    =  35 x ( 34 + 38 ) + 65 x 75 + 45

    =  35 x 72 + 65 x 75 + 45

    =  2520 + 4875 + 45

    =  2520 + 4920

    =  7440

c)     3 x 25 x 8 + 4 x 37 x 6 + 2 x 38 x 12

    =  ( 3 x 8 ) x 25 + ( 4 x 6 ) x 37 + ( 2 x 12 ) x 38

    =   24 x 25 + 24 x 37 + 24 x 38

    =   24 x ( 25 + 37 + 38 )

    =   24 x 100

    =   2400

a)29+132+237+868+763

=(132+868)+(237+763)+29

=     1000   +   1000    +29

=      2029

a,29+132+237+868+763

=29+(132+868)+(237+763)

=29+1000+1000

=2029

a, 298+132+237+868+763

= 298+(132+868)+(237+763)

=298+1000+1000

=298+1000×2

=298+2000

=2298

b, 35×68+35×31+35

=35×68+35×31+35×1

=35×(68+31+1)

=35×100

=3 500

c, 35×34+35×66

=35×(34+66)

=35×100

=3 500

d, ( 563+745)-(463+545)

= 563 + 745 - 463 - 545

= (563-463) + (745-545)

= 100 + 200

= 300

e, 73+86+968+914+3032

= 73+(86+914)+(968+3032)

=73+1000 + 4000

=73+5000

=5073

f, 4×8×25×1,25×27

= (4×25)×(8×1,25)×27

=100×10×27

=1000×27

=27 000

a, 2289

b, 3500

c, 3500

d, 300

e, 5073

f, 27000

\(a,289+132+237+868+763=289+\left(132+868\right)+\left(763+237\right)\)

\(=289+1000+1000=289+2000=2289\)

\(b,=35\times\left(68+31+1\right)=35\times100=3500\)

\(c,=35\times\left(34+66\right)=35\times100=3500\)

\(d,=563+745-463-545=\left(563-463\right)+\left(745-545\right)\)

\(=100+200=300\)

\(e,=73+\left(86+914\right)+\left(968+3032\right)=73+1000+4000=5073\)

\(f,=\left(4\times25\right)\times\left(8\times1,25\right)\times27=100\times10\times27=27000\)

  35.20.4/7.8.15

=10/3

cho mik nha

\(\frac{35\times20\times4}{7\times8\times15}\)

\(=\frac{5\times7\times5\times4\times4}{7\times2\times4\times3\times5}\)

\(=\frac{5\times4}{2\times3}\)

\(=\frac{10}{3}\)

35 x 20 x 4/7 x 8 x 15

= 5 x 7 x 2 x 10 x 4/7 x 4 x 2 x 5 x 3

= 10/3

Tk mk nha

A=(165+35)\(^2\) = 100\(^2\) = 10000

\(A=165^2+70.165+35^2=165^2+2.35.165+35^2=\left(165+35\right)^2=200^2=40000\)

\(C=5^4.7^4-\left(35^2-1\right)\left(35^2+1\right)=35^4-[\left(35^2\right)^2-1^2]=35^4-35^4+1=1\)

3/17 - 5/13 - 18/35 + 14/17 + 17/-35 - 8/13

=(3/17+14/17)+(-5/13-8/13)+(-18/35+17/35)

=1+(-1)+(-1/35)

=-1/35

Chúc bn học tốt

\(\frac{3}{17}-\frac{5}{13}-\frac{18}{35}+\frac{14}{17}\)\(+\frac{17}{-35}-\frac{8}{13}\)

\(=\left(\frac{3}{17}+\frac{14}{17}\right)\)\(-\left(\frac{18}{35}-\frac{-17}{35}\right)\)\(-\left(\frac{5}{13}+\frac{8}{13}\right)\)

\(=1-1-1\)\(=0\)

mình tính lộn kết quả bằng -1