TL :

a, ( -12/16 + 7/14 ) - ( 1/13 - 3/13 )

= ( -3/4 + 1/2 ) - (-2/13)

= (-3/4 + 2/4 ) - ( -2/13 )

= -1/4 - ( -2/13 )

= (-13/52 ) - (-8/52)

= -5/52

b, 10/11 + 4/11 : 4 - 1/8 = 10/11 + 1/11 - 1/8

= 11/11 - 1/8

= 1 -1/8 

= 8/8 - 1/8

= 7/8

HT

7/8 

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a) 2/9 - (1/20 + 2/9)

= 2/9 - 1/20 - 2/9

= (2/9 - 2/9) - 1/20

= 0 - 1/20

= -1/20

b) -3/14 + 2/13 + (-25/14) + (-15/13)

= (-3/14 - 25/14) + (2/13 - 15/13)

= -2 - 1

= -3

c) -3/11 + 11/8 - 3/8 + (-8/11)

= (-3/11 - 8/11) + (11/8 - 3/8)

= -1 + 1

= 0

d) 3/8 + (-1/4) - (7/12 - 1/6)

= 1/8 - 5/12

= -7/24

e) (1/3 + 12/67 + 13/41) - (79/67 - 28/41)

= 1/3 + 12/67 + 13/41 - 79/67 + 28/41

= 1/3 + (12/67 - 79/67) + (13/41 + 28/41)

= 1/3 - 1 + 1

= 1/3

nhanh k 10 k lun

nhyhvgfh

Trả lời :

a = 4

k mik nha bn

thank you nhiều 

cảm ơn

chúc học tốt

12 . 13 . 14 . 15 . 16 = 524160 => a = 4

Ta thấy, trong tích có 12 . 15 = 3. 4 . 3 . 5 = 9 . 4 . 5

Suy ra, 52a160 chia hết cho 9

Do 52a160 chia hết cho 9 nên ( 5 + 2 + a + 1 + 6 + 0 ) chia hết cho 9

=> 14 + a chia hết cho 9

Vì a là STN có 1 chữ số nên a nhận giá trị = 4 ( 14 + 4 = 18 , 18 chia hết cho 9 , thỏa mãn )

Vậy ta có a cần tìm = 4

12 . 13 . 14 . 15 . 16 = 524160

Duyệt nha bạn ! Chúc bạn học giỏi !

a) \(\frac{3}{5}\cdot\frac{13}{46}-\frac{1}{10}\cdot\frac{16}{23}=\frac{39-16}{10\cdot23}=\frac{1}{10}\)

b) \(\frac{3}{7}\cdot\frac{9}{26}-\frac{1}{14}\cdot\frac{1}{13}=\frac{27-1}{14\cdot13}=\frac{2\cdot13}{2\cdot7\cdot13}=\frac{1}{7}\)

c) Ta có: \(\dfrac{3}{5}+\dfrac{-5}{20}+\dfrac{30}{75}+\dfrac{-7}{4}\)

\(=\dfrac{3}{5}+\dfrac{2}{5}+\dfrac{-1}{4}+\dfrac{-7}{4}\)

\(=1-2=-1\)

Giải:

a)-1/12+4/3=-1/12+16/12=15/12=5/4

b)(-4/14-3/15)-(1/5-20/35-(-1)).7

=-17/35-22/35.7

=-17/35-22/5

=-171/35

c)3/5+-5/20+30/75+-7/4

=3/5+-1/4+2/5+-7/4

=(3/5+2/5)+(-1/4+-7/4)

=1+-2

=-1

d)5/6.-12/14+7/13

=-5/7+7/13

=-16/91

e)2/-9-5/-36-1/4

=-1/12-1/4

=-1/3

f)2/23+-5/12+7/18+21/23+-7/12

=(2/23+21/23)+(-5/12+-7/12)+7/18

=1+-1+7/18

=7/18

xcsxccsz

A. -14 - 7 - 12 - 24 

= - 21 - 12 - 24

= - 33 - 24

= - 57

B. -10 - 14 - 16 + 43

= - 24 - 16 + 43

= - 40 + 43

= - 83

C. 32 + |-23| - 57 - (-23)

= 32 + 23 - 57 +23

= 55 - 57 + 23

= - 2 + 23

= 21

D. |-8| + |-4| - (-12) + 5

= 8 + 4 + 12 + 5

= 12 + 12 + 5

= 24 + 5

= 29

E. |-13| - |-17| + (-20) - (-18) 

= 13 - 17 - 20 + 18

= - 4 - 17 - 20 + 18

= - 21 - 20 + 18

= - 41 + 18

= 23

A. -14-7-12-24=-21-36=-57

B. -10-14-16+43=-24+27=3

C.32+\(^{|-23|}\)-57-(-23)=32+23-57+23=55-80=-25

D.\(|-8|+|-4|\)-(-12)+5=8+4+12+5=12+17=29

E.\(|-13|-|-17|\)+(-20)-(-18)=13-17-20+18=-4-2=-6

thực hiện phép tính

a) -14 - 7 - 12 - 24

= -21 - 12 - 24

= -33 - 24

= -57

b) -10 - 14 - 16 + 43

= -24 - 16 + 43 

= -40 + 43

= 3

c) 32 + |-23| - 57 - (-23)

= 32 + 23 - 57 + 23

= 55 - 57 + 23

= -2 + 23

= 21

d) |-8| + |-4| -(-12) + 5

= 8 + 4 + 12 + 5

= 12 + 12 + 5

= 24 + 5

= 29

e) |-13| - |-17| + (-20) - (-18)

= 13 - 17 + (-20) + 18

= -4 + (-20) + 18

= -24 + 18

= -6

    t.i.c.k cho mk nha bn

b: =12+5/14-3-5/7-5-5/14

=4-5/7

=28/7-5/7=23/7

c: =(-2/5-11/10)+(7/11-7/11)

=-4/10-11/10=-15/10=-3/2

\(a,\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{5}{13}\cdot\dfrac{2}{9}\)

\(=\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{2}{13}\cdot\dfrac{5}{9}\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{7}{13}+\dfrac{8}{13}-\dfrac{2}{13}\right)\)

\(=\dfrac{5}{9}\cdot\dfrac{14}{13}\)

\(=\dfrac{70}{117}\)

\(d,\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}+\dfrac{-2}{5}\)

\(=\left(\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}\right)+\dfrac{-2}{5}\)

\(=0+\dfrac{-2}{5}\)

\(=\dfrac{-2}{5}\)