1.tính thuận tiện
a. 2/3 x 4/5 + 1/3 x 4/5
b. 2/3 x 4/5 - 1/3 x 4/5
c. 1/2 : 3/4 + 1/6 : 3/4
d. 1/2 : 3/4 - 1/6 : 3/4
tính bằng cách thuận tiện nhất
5,5+3/4-5+1/4
5/2x2/3+1/4:3/2
tính x ;
435-[ x +16]=425: 17
x x 1/4-3/4=6:3/4
x +2 3/4=5 2/3
5,5 + \(\dfrac{3}{4}\) - 5 + \(\dfrac{1}{4}\)
(5,5 - 5) + (\(\dfrac{3}{4}\) + \(\dfrac{1}{4}\))
= 0,5 + 1
= 1,5
\(\dfrac{5}{2}\) x \(\dfrac{2}{3}\) + \(\dfrac{1}{4}\) : \(\dfrac{3}{2}\)
= \(\dfrac{5}{2}\) x \(\dfrac{2}{3}\) + \(\dfrac{1}{4}\) x \(\dfrac{2}{3}\)
= (\(\dfrac{5}{2}\) + \(\dfrac{1}{4}\)) x \(\dfrac{2}{3}\)
= (\(\dfrac{10}{4}\) + \(\dfrac{1}{4}\)) x \(\dfrac{2}{3}\)
= \(\dfrac{11}{4}\) x \(\dfrac{2}{3}\)
= \(\dfrac{11}{6}\)
Tính \(x\):
435 - [\(x\) + 16] = 425 : 17
435 - [\(x\) + 16] = 25
[\(x\) + 16] = 435 - 25
\(x\) + 16 = 410
\(x\) = 410 - 16
\(x\) = 394
\(x\) x \(\dfrac{1}{4}\) - \(\dfrac{3}{4}\) = 6 : \(\dfrac{3}{4}\)
\(x\) \(\times\) \(\dfrac{1}{4}\) - \(\dfrac{3}{4}\) = 6 x \(\dfrac{4}{3}\)
\(x\) x \(\dfrac{1}{4}\) - \(\dfrac{3}{4}\) = 8
\(x\) x \(\dfrac{1}{4}\) = 8 + \(\dfrac{3}{4}\)
\(x\) x \(\dfrac{1}{4}\) = \(\dfrac{32}{4}\) + \(\dfrac{3}{4}\)
\(x\) x \(\dfrac{1}{4}\) = \(\dfrac{35}{4}\)
\(x\) = \(\dfrac{35}{4}\) : \(\dfrac{1}{4}\)
\(x\) = \(\dfrac{35}{4}\) x 4
\(x\) = 35
bài 1 tính
a. 32,5 - 3 x 0,87
8,5 x ( 1 và 1 phần 2 + 4 phần 4 ) : 5
b, 30,96 - 6,45 + 14,4 : 3
2 phần 5 ( 4 phần 5 - 1 phần 2)
bài 2 . tính bằng cách thuận tiện nhất
a, 2,5 x 12,5 x 8 x 0,4
b. 12 phần 15 x 5 phần 6 x 3 phần 20 x 32 phần 5
\(a.32,5-3\cdot0,87=32,5-2,61=29,89\)
\(8,5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8,5\cdot\left(\dfrac{3}{2}+\dfrac{4}{4}\right):5\\ =8,5\cdot\left(\dfrac{6}{4}+\dfrac{4}{4}\right):5\\ =8,5\cdot\dfrac{10}{4}:5\\ =\dfrac{85}{4}:5\\ =\dfrac{17}{4}\)
\(b.30,96-6,45+14,4:3=30,96-6,45+4,8\\ =29,31\)
\(\dfrac{2}{5}\cdot\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\cdot\left(\dfrac{8}{10}-\dfrac{5}{10}\right)\\ =\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{3}{25}\)
bài 2
\(a.2,5\cdot12,5\cdot8\cdot0,4=\left(2,5\cdot0,4\right)\left(12,5\cdot8\right)\\ =1\cdot100=100\)
b,\(\dfrac{12}{15}\cdot\dfrac{5}{6}\cdot\dfrac{3}{20}\cdot\dfrac{32}{5}=\dfrac{12\cdot5\cdot3\cdot32}{15\cdot6\cdot20\cdot5}\\ =\dfrac{3\cdot4\cdot5\cdot3\cdot4\cdot8}{3\cdot5\cdot2\cdot3\cdot5\cdot4\cdot5}=\dfrac{16}{25}\)
Bài 1:
a) \(32.5-3\cdot0.87=32.5-2.61=29.89\)
\(8.5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8.5\cdot\dfrac{5}{2}:5=\dfrac{17}{2}\cdot\dfrac{5}{2}:5=\dfrac{85}{4}\cdot\dfrac{1}{5}=\dfrac{17}{4}\)
b) \(30.96-6.45+14.4:3=24.51+4.8=29.33\)
\(\dfrac{2}{5}\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\left(\dfrac{8}{10}-\dfrac{5}{10}\right)=\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{6}{50}=\dfrac{3}{25}\)
Bài 1. Tính bằng cách thuận tiện nhất:
a)(1/3+1/5)x1/4 b)5/3 x 4/5 x 6/7 c) 2/5 x 3/7 + 2/5 x 4/7
a: =8/15x1/4=2/15
b: \(=\dfrac{5}{3}\cdot\dfrac{4}{5}\cdot\dfrac{6}{7}=\dfrac{24}{21}=\dfrac{8}{7}\)
c: \(=\dfrac{2}{5}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\)
tính bằng cách thuận tiện nhất :
1/2 x 2/3 x 3/4 x 4/5 x 5/6
1/10 x 2/9 x 3/8 x 4/7 x 5/6 x 6/5 x 7/4 x 3/8 x 9/2
2 năm sau mày sẽ chết do dịch bệnh
Tính bằng cách thuận tiện:
a) 2/3 x 4/9 + 2/3 x 5/9
b, 7/5 x 3/4 - 1/2 x 3/4
c, ( 5/6 + 5/8 ) x 2/3
a.\(\dfrac{2}{3}\times\dfrac{4}{9}+\dfrac{2}{3}\times\dfrac{5}{9}=\dfrac{2}{3}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{2}{3}\times1=\dfrac{2}{3}\)
b.\(\dfrac{7}{5}\times\dfrac{3}{4}-\dfrac{1}{2}\times\dfrac{3}{4}=\dfrac{3}{4}\times\left(\dfrac{7}{5}-\dfrac{1}{2}\right)=\dfrac{3}{4}\times\dfrac{9}{10}=\dfrac{27}{40}\)
c.\(\left(\dfrac{5}{6}+\dfrac{5}{8}\right)\times\dfrac{2}{3}=\dfrac{35}{24}\times\dfrac{2}{3}=\dfrac{35}{36}\)
a) 2/3 x 4/9 + 2/3 x 5/9
=2/3 x ( 4/9 + 5/9)
= 2/3 x 1
= 2/3
b, 7/5 x 3/4 - 1/2 x 3/4
= ( 7/5 - 1/2 ) x 3/4
= 9/10 x 3/4
= 21/40
c, ( 5/6 + 5/8 ) x 2/3
= 35/24 x 2/3
= 35/36
a) \(\dfrac{2}{3}\times\dfrac{4}{9}+\dfrac{2}{3}\times\dfrac{5}{9}=\dfrac{2}{3}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{2}{3}\times1=\dfrac{2}{3}\)
b) \(\dfrac{7}{5}\times\dfrac{3}{4}-\dfrac{1}{2}\times\dfrac{3}{4}=\left(\dfrac{7}{5}-\dfrac{1}{2}\right)\times\dfrac{3}{4}=\dfrac{9}{10}\times\dfrac{3}{4}=\dfrac{27}{40}\)
c) \(\left(\dfrac{5}{6}+\dfrac{5}{8}\right)\times\dfrac{2}{3}=\left(\dfrac{20}{24}+\dfrac{15}{24}\right)\times\dfrac{2}{3}=\dfrac{35}{24}\times\dfrac{2}{3}=\dfrac{35}{36}\)
Tính bằng cách thuận tiện nhất:
5 3/4 : 3 + 2 1/4 x 1/3 - 1/8
3/5 : 5/6 : 6/7 : 7/8 + 2/5 + 23/35
\(5\dfrac{3}{4}:3+2\dfrac{1}{4}\times\dfrac{1}{3}-\dfrac{1}{8}=\left(5\dfrac{3}{4}+2\dfrac{1}{4}\right)\times\dfrac{1}{3}-\dfrac{1}{8}\\ =8\times\dfrac{1}{3}-\dfrac{1}{8}=\dfrac{8}{3}-\dfrac{1}{8}=\dfrac{61}{24}\\ ----\\ \dfrac{3}{5}:\dfrac{5}{6}:\dfrac{6}{7}:\dfrac{7}{8}+\dfrac{2}{5}+\dfrac{23}{35}\\ =\dfrac{3}{5}\times\dfrac{6}{5}\times\dfrac{7}{6}\times\dfrac{8}{7}+\dfrac{2}{5}+\dfrac{23}{35}=\dfrac{18}{25}\times\dfrac{4}{3}+\dfrac{2}{5}+\dfrac{23}{35}=\dfrac{353}{175}\)
1:tính bằng cách thuận tiện nhất:
a)54 x 113 + 45 x 113 + 113 b)3/7 + 4/9 + 8/14 + 10/18
2:tính giá trị biểu thức
a)9/5 - 1/2 + 1/3
b)12/9 x 1/12 + 1/6 x 12/9
c)3/4 x (5/6 + 2/3)
d)3/2 - 2/3 : 2
1.a,=(54+45+1).113
=100.113
=11300
b,=(3/7+8/14)+(4/9+10/18)
=1+1
=2
2.a,=13/10+1/3
=49/30
b,=12/9.(1/12+1/6)
=12/9.1/4
=1/3
c,=3/4.3/2
=9/8
d,=3/2-1/3
=7/6
1:tính bằng cách thuận tiện nhất:
a)54 x 113 + 45 x 113 + 113
= 54 x 113 + 45 x 113 + 113x1
=113 x(54+45+1)
= 113x100
=1300
b)3/7 + 4/9 + 8/14 + 10/18
=(3/7+8/14)+(4/9+10/18)
= 1 + 1
=2
a) Tính bằng cách thuận tiện
12/15 + 4/3 + 1/4 + 3/4 + 5/3 + 3/15
b) Tìm X
X x 3/4 = 1/6 x 3/5 x 6/5 x 5/3 (MÌNH CẦN GẤP ĐỂ NỘP)
a. \(=\left(\dfrac{12}{15}+\dfrac{3}{15}\right)+\left(\dfrac{4}{3}+\dfrac{5}{3}\right)+\left(\dfrac{1}{4}+\dfrac{3}{4}\right)\\ =1+2+1=4\)
b. \(x\times\dfrac{3}{4}=\dfrac{1\times3\times6\times5}{6\times5\times5\times3}\\ x\times\dfrac{3}{4}=\dfrac{1}{5}\\ x=\dfrac{1}{5}:\dfrac{3}{4}\\ x=\dfrac{4}{15}\)
a.
(12/15+3/15)+(4/3+5/3)+(1/4+3/4)
=1+3+1=5
b.X x 3/4=1/5
X=1/5:3/4
X=4/15
a) Tính bằng cách thuận tiện nhất :
1/2 x 1/3 + 1/3 x 1/4 + 1/4 x 1/5 + 1/5 x 1/6 = ........
b) Tính :
( 1 - 1/2 ) x ( 1 - 1/3 ) x ( 1 - 1/4 ) = ........
( 1 + 1/2 ) : ( 1 + 1/3 ) : ( 1 + 1/4 ) = ........
Mọi người nhớ kb vs mk nha
a) \(\frac{1}{2}\times\frac{1}{3}+\frac{1}{3}\times\frac{1}{4}+\frac{1}{4}\times\frac{1}{5}+\frac{1}{5}\times\frac{1}{6}=\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(=\frac{1}{2}-\frac{1}{6}=\frac{3}{6}-\frac{1}{6}=\frac{2}{6}=\frac{1}{3}\)
b) \(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}=\frac{1}{4}\)
\(a)\frac{1}{2}\times\frac{1}{3}+\frac{1}{3}\times\frac{1}{4}+\frac{1}{4}\times\frac{1}{5}+\frac{1}{5}\times\frac{1}{6}\)
\(\Rightarrow\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}\)
\(\Rightarrow\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(\Rightarrow\frac{1}{2}-\frac{1}{6}\)
\(\Rightarrow\frac{1}{3}\)
\(b)\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\)
\(=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\)
\(=\frac{1\times2\times3}{2\times3\times4}\)
\(=\frac{1}{4}\)
\(b)\left(1-\frac{1}{2}\right)\div\left(1-\frac{1}{3}\right)\div\left(1-\frac{1}{4}\right)\)
\(=\frac{1}{2}\div\frac{2}{3}\div\frac{3}{4}\)
\(=\frac{1}{2}\times\frac{3}{2}\times\frac{4}{3}\)
\(=\frac{1\times3\times2\times2}{2\times2\times3}\)
\(=1\)