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x=(1,1-1+0,064)*11/4

x=0,451

a) (2/5 x 25/29) + (3/5 x 25/29)
= (50/145) + (75/145)
= 125/145

b) (5/2 x 3/7) - (3/14 : 6/7)
= 15/14 - (3/14 x 7/6)
= 15/14 - 1/2
= (30/28) - (14/28)
= 16/28
= 4/7

c) (15/4 : 5/12) - (6/5 : 11/15)
= (15/4 x 12/5) - (6/5 x 15/11)
= 180/20 - 90/55
= 9 - 18/11
= (99/11) - (18/11)
= 81/11
= 7 4/11

a) (2/3) + (20/21 x 3/2 x 7/5)
= 2/3 + (60/210)
= 2/3 + 2/7
= (14/21) + (6/21)
= 20/21

b) (5/17 x 21/32 x 47/24 x 0)
= 0

c) (11/3 x 26/7) - (26/7 x 8/3)
= (286/21) - (208/21)
= 78/21
= 3 9/21
= 3 3/7

a) (25/8) : x = 5/16
=> (25/8) x (16/5) = x
=> 4 = x

b) x + (7/15) = 6/15
=> x = (6/15) - (7/15)
=> x = -1/15

c) x : (28/49) = 7/12
=> x x (49/28) = 7/12
=> x = (7/12) x (28/49)
=> x = 1/2

a) 6 x x = (5/8) : (3/4)
=> 6x = (5/8) x (4/3)
=> 6x = 20/24
=> 6x = 5/6
=> x = (5/6) / 6
=> x = 5/36

câu,b,không,đủ,thông,tin,nhan,bạn.

= 13/30

a) c1 := -2/-5+-5/-6+4/5

=2/5+5/6+4/5

=12/30+25/30+24/30

=61/30

c2:=(2/5+4/5)+4/5

=(2/5+4/5)+5/6

=6/5+5/6

=36/30+25/30

=61/30

b)c1:=-3/-4+11/-15+-1/2

=3/4+-11/15+-1/2

=45/60+-44/30+-30/60

-29/30

c2:=3/4+(-11/15+-1/2)

=(3/4+-1/2)+-11/15

=(3/4+-2/4)+-11/5

=1/4+-11/15

=15/60+-44/60

=-29/60

Lời giải:

a.

$\frac{5}{15}-\frac{1}{6}\times \frac{2}{5}=\frac{5}{15}-\frac{1}{15}=\frac{4}{15}$

b.

$\frac{8}{24}+\frac{3}{4}:\frac{1}{8}=\frac{1}{3}+6=\frac{19}{3}$

c.

$\frac{1}{7}: \frac{2}{8}-\frac{1}{7}=\frac{1}{7}\times 4-\frac{1}{7}$

$=\frac{1}{7}\times (4-1)=\frac{1}{7}\times 3=\frac{3}{7}$

=(4x0.25)x(2x0.5)

=1x1=1