\(=\left(1\frac{4}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)+0,5=1+1+0,5=2,5\)

\(\Rightarrow A=\left(\frac{27}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)+\frac{1}{2}\)

\(\Rightarrow A=1+1+\frac{1}{2}\)

\(\Rightarrow A=\frac{5}{2}\)

tíc mình nha

A=1+1+1/2

A=5/2

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

-23.63+23.21-58.23

=23.(-63)+23.21-58.23

=23.(21-63-58)

=23.(-100)

=-2300

\(1\dfrac{4}{23}+\left(\dfrac{5}{21}-\dfrac{4}{23}\right)+\dfrac{16}{21}-\dfrac{1}{2}\)

\(=1\dfrac{4}{23}-\dfrac{4}{23}+\dfrac{5}{21}+\dfrac{16}{21}+\dfrac{1}{2}\)

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

\(=\dfrac{3}{2}\)

1 4/23 + ( 5/21-4/23 ) + 16/21 - 1/2
=1 4/23 - 4/23 + 5/21 + 16/21 + 1/2
= 1+1-1/2
=3/2

a,  2 17 + 17 2 9 15 - 3 15 2 4 - 4 2

=  2 17 + 17 2 9 15 - 3 15 16 - 16

=  2 17 + 17 2 9 15 - 3 15 . 0

= 0

b,  1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 3 8 - 81 2 )

=  1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 3 4 . 2 - 81 2 )

=  1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 81 2 - 81 2 )

=  1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) . 0

= 0

c,  7 24 + 7 23 : 7 22

=  7 24 : 7 22 + 7 23 : 7 22

=  7 24 - 22 + 7 23 - 22

=  7 2 + 7 1

= 49 + 7 = 56

Lời giải :

a ) \(1\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}\)

\(=\left(1\dfrac{4}{23}-\dfrac{4}{23}\right)+\left(\dfrac{5}{21}+\dfrac{16}{21}\right)+0,5\)

\(=2,5\)

b ) \(\dfrac{3}{7}.19\dfrac{1}{3}-\dfrac{3}{7}.33\dfrac{1}{3}\)

\(=\dfrac{3}{7}\left(19\dfrac{1}{3}-33\dfrac{1}{3}\right)\)

\(=\dfrac{3}{7}\left(19-33\right)\)

\(=\dfrac{3}{7}\left(-14\right)\)

\(=-6\)

c ) \(9\left(-\dfrac{1}{3}\right)^3+\dfrac{1}{3}\)

\(=9\left(-\dfrac{1}{27}\right)+\dfrac{1}{3}\)

\(=-\dfrac{1}{3}+\dfrac{1}{3}\)

\(=0\)

d ) \(15\dfrac{1}{4}\div\left(-\dfrac{5}{7}\right)-25\dfrac{1}{4}\div\left(-\dfrac{5}{7}\right)\)

\(=\left(15\dfrac{1}{4}-25\dfrac{1}{4}\right)\div\left(-\dfrac{5}{7}\right)\)

\(=-10\left(-\dfrac{7}{5}\right)\)

\(=14\)

[ (-4) x 25 ] x 23 = -100 x 23 = -2300

--2300