21. Tính giá trị biểu thức:
a) 2989 + 11 x 56 c) 2036 - 3025 : 5
b) 5264 – 274 x 16 d) (2100 + 45) x 4 – 249
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nhân chia trước cộng trừ sau làm theo thứ tự đó là ra nhé
a)2989+11x56
=2989+(11x56)
=2989+616
=3605
b)5264-274x16
=5264-(274x16)
=5264-4384
=880
c)2036-3025:5
=2036-(3025:5)
=2036-605
=1431
d)(2100+45)x4-249
=(2145x4)-249
=8580-249
=8331
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.
(10 - 1 \(\dfrac{1}{6}\) x \(\dfrac{6}{7}\)) : ( 21: \(\dfrac{11}{2}\) + 5\(\dfrac{2}{11}\) )
( 10 \(\dfrac{7}{6}\) x \(\dfrac{6}{7}\) ) : ( 21 : \(\dfrac{11}{2}\) + \(\dfrac{57}{11}\) )
(10 - 1) : ( \(\dfrac{42}{11}\) + \(\dfrac{57}{11}\) )
= 9 : 9
= 1
=> đáp án : 1
=(10 - 1 1/6 x 6/7) : ( 21: 11/2 + 5 2/11)
=( 10 7/6 x 6/7 ) : ( 21 : 11/2 + 57/11)
=(10 - 1) : ( 42/11 + 57/11 )
= 9 : 9
=1
=(10 - 1 1/6 x 6/7) : ( 21: 11/2 + 5 2/11)
=( 10 7/6 x 6/7 ) : ( 21 : 11/2 + 57/11)
=(10 - 1) : ( 42/11 + 57/11 )
= 9 : 9
=1
=(10 - 1 1/6 x 6/7) : ( 21: 11/2 + 5 2/11)
=( 10 7/6 x 6/7 ) : ( 21 : 11/2 + 57/11)
=(10 - 1) : ( 42/11 + 57/11 )
= 9 : 9
=1
Bài 1:
a) \(\frac{16}{15}.\frac{\left(-5\right)}{14}.\frac{54}{24}.\frac{56}{21}\)
\(=\frac{4.2.2}{5.3}.\frac{\left(-5\right)}{2.7}.\frac{3.3}{4}.\frac{8}{3}\)
\(=\frac{4.2.2.\left(-5\right).3.3.8}{5.3.2.7.4.3}\)
\(=\frac{-16}{7}\)
b) \(\frac{7}{3}.\frac{\left(-5\right)}{2}.\frac{15}{21}.\frac{4}{\left(-5\right)}\)
\(=\frac{7}{3}.\frac{\left(-5\right)}{2}.\frac{5}{7}.\frac{2.2}{\left(-5\right)}\)
\(=\frac{7.\left(-5\right).5.2.2}{3.2.7.\left(-5\right)}\)
\(=\frac{10}{3}\)
Bài 2:
a) \(\frac{21}{24}.\frac{11}{9}.\frac{5}{7}=\frac{7}{8}.\frac{11}{9}.\frac{5}{7}=\frac{11.5}{8.9}=\frac{55}{72}\)
b) \(\frac{5}{23}.\frac{17}{26}+\frac{5}{23}.\frac{9}{26}\)
\(=\frac{5}{23}.\left(\frac{17}{26}+\frac{9}{26}\right)=\frac{5}{23}.1=\frac{5}{23}\)
c) \(\left(\frac{3}{29}-\frac{1}{5}\right).\frac{29}{3}=\frac{3}{29}.\frac{29}{3}-\frac{1}{5}.\frac{29}{3}\)
\(=1-1\frac{14}{15}=\frac{14}{15}\)
Bài 3:
a) x/5 = 2/5
=> x =2
b) -4/x = 20/14 = 10/7
=> -4/x = 10/7
=> x.10 = (-4).7
x.10 = - 28
x= -28 :10
x= -2,8
c) 4/7 = 12/x = 12/ 21
=> 12/x = 12/21
=> x = 21
d) 3/7 = x / 21 = 9/21
=> x/21 = 9/21
=> x= 9
a, 15 . { 32 : [ 6 - 5 + 5 ( 9 : 3 ) ] + 3 } - 2018 0
= 15.{32:[1+15]+3}–1
= 15.5–1
= 74
b, 25 . { 2 7 : [ 12 - 4 + 2 2 . 16 : 2 3 ] - 2 4 }
= 25.{128:[8+4.2]–16}
= 25.24
= 600
c, 2019 . { 101 - 1000 : [ 2 2 . 2 3 + 5 6 : 5 3 - 6 2 : 11 - 2018 0 ] }
= 2019.{101–1000:[(32+125–36):11–1]}
= 2019.{101–1000:[121:11–1]}
= 2019.{101–1000:10}
= 2019.1
= 2019
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