TL

a, 100005175327

b, 148904438

c, 10746660

HT

Mình mất 5 phút để giải, bạn mất 1 giây để t.i.c.k, nhớ t.i.c.k mình nhá

C1 : 5/24 x 5/12 x 24

=    5/24 x ( 5/12 x 24 ) 

=   5/24  x   10 

=         50/24

=         25/12

C2 :            5/24 x 5/12 x 24

=             ( 5/24 x 24 ) x ( 5/12 ) 

=                    5 x (  5/12 )  

=                25/12

Chúc em học giỏi !!! 

Cách 1 : 5/24 x 5/12 x 24 = (5/24 x 24) x 5/12

                                        = 5 x 5/12 = 25/12

Cách 2 : 5/24 x 5/12 x 24 = 5/24 x (5/12 x 24)

                                         = 5/24 x 10 = 25/12

c1

5/24x5/12x24

=5/24x(5/12x24)

=5/24x10

=50/24

=25/12

c2

5/24x5/12x24

=(5/24x24)x5/12

=5x5/12=25/12

~~ học tốt nhé!!

$B=636363\cdot37-373737\cdot63$

$=63\cdot10101\cdot37-37\cdot10101\cdot63$

$=0$

ưeqfrety6yhythythyt

B = 636363 . 37 - 373737.63

B = 63. 10101 . 37 - 37. 10101. 63

B = 0 

(Vì cả hai vế đều giống nhau)

1) A=\(\dfrac{7}{1.3}+\dfrac{7}{3.5}+\dfrac{7}{5.7}+...+\dfrac{7}{99.101}\)=\(\dfrac{7.2}{1.3.2}+\dfrac{7.2}{3.5.2}+\dfrac{7.2}{5.7.2}+...+\dfrac{7.2}{99.101.2}\)=

\(\dfrac{7}{2}\left(\text{​​}\dfrac{2}{1.3}+\dfrac{2}{3.5}+\dfrac{2}{5.7}+...+\dfrac{2}{99.101}\right)\)=

\(\dfrac{7}{2}\left(\text{​​}1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}...+\dfrac{1}{99}-\dfrac{1}{101}\right)\)=

\(\dfrac{7}{2}\left(\text{​​}1-\dfrac{1}{101}\right)\)=\(\dfrac{7}{2}.\dfrac{100}{101}=\dfrac{350}{101}\)

2) A=\(\dfrac{1}{2}+\dfrac{2}{2.4}+\dfrac{3}{4.7}+\dfrac{4}{7.11}+\dfrac{5}{11.16}\)=\(\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}\)

=\(\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{16}\)=\(1-\dfrac{1}{16}=\dfrac{15}{16}\)

\(a,=-17+91-91+17+2011=\left(-17+17\right)+\left(91-91\right)+2011\)

\(=0+0+2011=2011\)

b)\(=\dfrac{4}{7}+\dfrac{1}{6}-0,375.4=\dfrac{31}{42}-\dfrac{3}{2}=-\dfrac{16}{21}\)

\(b)\) \(\dfrac{4}{7}\) + \(\dfrac{5}{6}\) : \(5\) \(- 0,375 .(-2)\)²\(=\) \(\dfrac{4}{7}\) + \(\dfrac{1}{6}\) - \(0,375\) . \(4\)

= \(\dfrac{4}{7}\) + \(\dfrac{1}{6}\) - \(\dfrac{3}{2}\) = \(\dfrac{4.6}{42}\) +  \(\dfrac{1.7}{42}\) - \(\dfrac{3.21}{42}\) = \(-\)\(\dfrac{16}{21}\)

Ta có (1+1/2)x(1+1/3)×.....×(1+1/2010)

=3/2x4/3x.....x2009/2010x2010/2011=2011/2

\(=\dfrac{3}{7}\cdot\left(\dfrac{4}{9}+\dfrac{5}{9}+1\right)=\dfrac{3}{7}\cdot2=\dfrac{6}{7}\)

\(=\dfrac{3}{7}\times\dfrac{4}{9}\times\dfrac{5}{9}\times\dfrac{3}{7}+\dfrac{3}{7}=\dfrac{3}{7}\times\left(\dfrac{4}{9}+\dfrac{5}{9}+1\right)=\dfrac{3}{7}\times2=\dfrac{6}{7}\)

=3/7 x (4/9 + 5/9) = 3/7 x1 =3/7

Trả lời :

\(\frac{1998\times1996+1997\times11+1985}{1997\times1996-1995\times1996}\)

\(=\frac{1998\times1996+\left(1996+1\right)\times11+1985}{1996\times\left(1997-1995\right)}\)

\(=\frac{1998\times1996+1996\times11+11+1985}{1996\times2}\)

\(=\frac{1998\times1996+1996\times11+1996}{1996\times2}\)

\(=\frac{1996\times\left(1998+11+1\right)}{1996\times2}\)

\(=\frac{2010}{2}\)

\(=1005\)