a, 24/-42 = -24/42= -4x6/7x6 =-4/7

b,-24/36 = -2x12/3x12 =-2/3

c,-8/56= -1x8/7x8 =-1/7

d,29/-87= -29/87 =-1x29/3x29 =-1/3

e, -3x35/42x9 =-1x3x5x7/6x7x3x3  =-1x5/3x6 =-5/18

f,-45045 / 6006000=-45x1001 /6000x1001=45/6000=3x15/15x400=3/400

\(a.\frac{-4}{7},b.\frac{-2}{3},c.\frac{-1}{7},d.\frac{-1}{3},e.\frac{-5}{18},f.\frac{-3}{400}\)

a) Vì \(\frac{-24}{42}=-\frac{24:6}{42:6}=-\frac{4}{7};\frac{32}{-56}=-\frac{32:8}{56:8}=-\frac{4}{7}\)

Mà \(-\frac{4}{7}=-\frac{4}{7}\)

\(\Rightarrow\frac{-24}{42}=\frac{32}{-56}\)

b) Vì \(\frac{36}{84}=\frac{36:12}{84:12}=\frac{3}{7};\frac{42}{98}=\frac{42:14}{98:14}=\frac{3}{7}\)

Mà \(\frac{3}{7}=\frac{3}{7}\) 

\(\Rightarrow\frac{36}{84}=\frac{42}{98}\) 

c) Vì \(\frac{1717}{2323}=\frac{1717:101}{2323:101}=\frac{17}{23};\frac{171717}{232323}=\frac{171717:10101}{232323:10101}=\frac{17}{23}\)

Mà \(\frac{17}{23}=\frac{17}{23}\) 

\(\Rightarrow\frac{1717}{2323}=\frac{171717}{232323}\) 

Remember to k to me. Make friends with me, too!!!

a: \(\left(24-234\right)+\left(234-24-77\right)\)

\(=24-234+234-24-77\)

\(=\left(24-24\right)+\left(234-234\right)-77\)

=0+0-77

=-77

b: \(\left(13-135+49\right)-\left(13+49\right)\)

\(=13-135+49-13-49\)

\(=\left(13-13\right)+\left(49-49\right)-135\)

=0+0-135

=-135

c: \(159-524-\left(59-424\right)\)

\(=159-524-59+424\)

\(=\left(159-59\right)-\left(524-424\right)\)

=100-100

=0

d: \(\left(36+79\right)+\left(145-79-36\right)\)

\(=36+79+145-79-36\)

\(=\left(36-36\right)+\left(79-79\right)+145\)

=0+0+145

=145

e: \(334-\left(117+234\right)+\left(42+117\right)\)

\(=334-117-234+42+117\)

\(=\left(334-234\right)+\left(117-117\right)+42\)

=100+0+42

=142

f: \(271-\left[\left(-43\right)+271-\left(-17\right)\right]\)

\(=271+43-271+\left(-17\right)\)

\(=\left(271-271\right)+\left(43-17\right)\)

=0+26

=26

Điền dấu(> ; < ; =) vào chỗ thích hợp

a) 24 + 32.. <  ..16 + 43

b) 58 - 25.   >  ..67 - 36

c) 42 + 13.  =  ..88 - 33

a.<

b.>

c.=

k ai giờ

UCLN(54,42,48)=6;UCLN(24,36,72)=12

UCLN(180,168)=12;UCLN(48,72)=24

xrminhmk...

a.6

b.12

c.12

d.24

bảo đảm đúng

a, BCNN(210;280) = 840 => BC(210;280) = 840k (k ∈ N)

b, BCNN(105;135) = 945 => BC(105;135) = 945k (k ∈ N)

c, BCNN(24;36) = 72 => BC(24;36) = 72k (k ∈ N)

d, BCNN(48;80;72) = 720 => BC(48;80;72) = 720k (k ∈ N)

e, BCNN(42;55;91) = 30030 => BC(42;55;91) = 30030k (k ∈ N)

f, BCNN(12;36;102) = 612 => BC(12;36;102) = 612k (k ∈ N)

\(\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+...+\frac{89}{90}\)

\(=1-\frac{1}{2}+1-\frac{1}{6}+1-\frac{1}{12}+1-\frac{1}{20}+...+1-\frac{1}{90}\)

\(=9-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{90}\right)\)

\(=9-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}\right)\)

\(=9-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{9}-\frac{1}{10}\right)\)

\(=9-\left(1-\frac{1}{10}\right)\)

\(=9-\frac{9}{10}=\frac{81}{10}\)

a, 12+18+24+30+36+42

=6.2+6.3+6.4+6.5+6.6+6.7

=6.(2+3+4+5+6+7)

=6.27

=162

b, mm+pp+xx+yy

=11.m+11.p+11.x+11.y

=11.(m+p+x+y)

c, 1212+2121+4242+2424

=12.101+21.101+42.101+24.101

=(12+21+42+24).101

=99.101

=9999