(2/3.5/7 + 2/3: 7/2). -1/3

=(10/21 + 2/3x2/7 ) . -1/3

=(10/21 + 4/21) . -1/3

=-10/63 - 4/63

=-14/63

(2/3.5/7+2/3:7/2)-1/3

=(2/3.5/7+2/3x2/7)-1/3

=[2/3.(5/7+2/7)]-1/3

=[2/3x1]-1/3

=2/3-1/3

=1/3

HT

=[\(\left(\frac{2}{3}.\frac{5}{7}+\frac{2}{3}.\frac{2}{7}\right).\left(\frac{-1}{3}\right)\)]

=[\(\left(\frac{2}{3}\right).\left(\frac{5}{7}+\frac{2}{7}\right).\left(\frac{-1}{3}\right)\)]

=[\(\left(\frac{2}{3}.1\right).\frac{-1}{3}\)]

=\(\frac{-1}{3}\)

giúp tớ với

Câu 1: 

a) \(=\frac{42}{5}:\frac{14}{5}\)

\(=3\)

b)

 \(=15-\frac{7}{3}:\left(\frac{4}{9}-\frac{1}{6}\right)\)

\(=15-\frac{7}{3}:\frac{4}{9}+\frac{7}{3}:\frac{1}{6}\)

\(=15-\frac{21}{4}+14\)

\(=29-\frac{21}{4}=29-5-\frac{1}{4}\)

\(=24-\frac{1}{4}=\frac{95}{4}\)

Câu 9

a) 2/15 + (-3/5)

= 2/15 - 3/5

= 2/15 - 9/15

= -7/15

b) -5/7 + 3/7 . (-2/9)

= -5/7 - 2/21

= -15/21 - 2/21

= -17/21

c) 5/16 - (7/15 - 3/16) + 17/30

= 5/16 - 7/15 + 3/16 + 17/30

= (5/16 + 3/16) + (17/30 - 14/30)

= 1/2 + 1/10

= 5/10 + 1/10

= 6/10

= 3/5

\(a,\dfrac{2}{15}+\left(-\dfrac{3}{5}\right)\\ =\dfrac{2}{15}-\dfrac{3}{5}\\ =\dfrac{2}{15}-\dfrac{9}{15}\\ =-\dfrac{7}{15}\\ b,-\dfrac{5}{7}+\dfrac{3}{7}\times\left(-\dfrac{2}{9}\right)\\ =-\dfrac{5}{7}-\dfrac{2}{21}\\ =-\dfrac{15}{21}-\dfrac{2}{21}\\ =-\dfrac{17}{21}\\ c,\dfrac{5}{16}-\left(\dfrac{7}{15}-\dfrac{3}{16}\right)+\dfrac{17}{30}\\ =\dfrac{5}{16}-\dfrac{7}{15}+\dfrac{3}{16}+\dfrac{17}{30}\\ =\left(\dfrac{5}{16}+\dfrac{3}{16}\right)-\left(\dfrac{17}{15}+\dfrac{17}{30}\right)\\ =\dfrac{1}{2}-\dfrac{17}{10}\\ =\dfrac{5}{10}-\dfrac{17}{10}\\ =-\dfrac{6}{5}.\)

\(34\times76+66\times110+34\times34\)

\(=34\times\left(76+34\right)+66\times110\)

\(=34\times110+66\times110=110\times\left(34+66\right)=110\times100=110000\)

34 x 76 + 66 x 110 + 34 x 34

= 34 x ( 76 + 34 ) + 66 x 110

= 34 x 110 + 66 x 110

= 110 x ( 34 + 66 )

= 110 x 100

= 11 000

=))

\(-23\cdot63+23\cdot21-58\cdot23\)

\(=23\left(-63+21-58\right)\)

\(=23\cdot\left(-100\right)\)

\(=-2300\)

Trả lời:

-23 . 63 + 23 . 21 - 58 . 23

= 23 . (-63 + 21 - 58)

= 23 . (-100)

= -2300

Hok tốt!

Vuong Dong Yet

Dấu "." là dấu nhân

Bg

 (7⁶⁵.23 + 7⁶⁵.26) : 7⁶⁴ - 2⁶.5

= 7⁶⁵.(23 + 26) : 7⁶⁴ - 2⁶.5

= 7⁶⁵.49 : 7⁶⁴ - 2⁶.5

= 7⁶⁵.7² : 7⁶⁴ - 2⁶.5

= 7⁶⁷ : 7⁶⁴ - 2⁶.5

= 7³ - 2⁶.5

= 343 - 64.5

= 343 - 320

= 23

Ta có: \(\left(7^{65}\times23+7^{65}\times26\right):7^{64}-2^6\times5\)

     \(=7^{65}\times\left(23+26\right):7^{64}-64\times5\)

     \(=7\times49-64\times5\)

     \(=7\times49-64\times5\)

     \(=343-320\)

     \(=23\)

Lời giải:

$=3.17+(3.120-3.17)=3.17+3.120-3.17$

$=(3.17-3.17)+3.120=3.120=360$

-3.(-17)+3.(120-17)

= 3.17 + 3.120 - 3.17

= (3.17-3.17) + 3.120

= 0 + 360 = 360

Lời giải:

$-3(-17)+3(120-17)=3.17+3.120-3.17=3.120=360$