Tính: 2 1 4 x 3 2 5
bài1. tính : a. 3 và 2/5 - 1/2 b. 4/5 + 1/5 x 3/4 c. 3 và 1/2 x 1 và 1/7 d. 4 và 1/6 : 2 và 1/3
bài2 : tính : a. 3 x 1/2 +1/4 x1/3 b. 1 và 4/5 - 2/3 : 2 và 1/3
bài 3 tìm x: a. X x 4/5 = 2 và 1/2 b. x : 3/2 = 11/4 - 5/2
sos
Bài 1
a) 3 2/5 - 1/2
= 17/5 - 1/2
= 34/10 - 5/10
= 29/10
b) 4/5 + 1/5 × 3/4
= 4/5 + 3/20
= 16/20 + 3/20
= 19/20
c) 3 1/2 × 1 1/7
= 7/2 × 8/7
= 4
d) 4 1/6 : 2 1/3
= 25/6 : 7/3
= 25/14
Bài 2
a) 3 × 1/2 + 1/4 × 1/3
= 3/2 + 1/12
= 18/12 + 1/12
= 19/12
b) 1 4/5 - 2/3 : 2 1/3
= 9/5 - 2/3 : 7/3
= 9/5 - 2/7
= 63/35 - 10/35
= 53/35
Bài 1
a) 3 2/5 - 1/2
= 17/5 - 1/2
= 34/10 - 5/10
= 29/10
b) 4/5 + 1/5 × 3/4
= 4/5 + 3/20
= 16/20 + 3/20
= 19/20
c) 3 1/2 × 1 1/7
= 7/2 × 8/7
= 4
d) 4 1/6 : 2 1/3
= 25/6 : 7/3
= 25/14
bủh
1.Tính tổng
a) S = 1 + 2 + 2^2 + 2^3 + ... + 2^2022
b) S = 3 + 3^2 + 3^3 + ... + 3^2022
c) S = 4 + 4^1 + 4^2 + 4^3 + ... + 4^2022
d) S = 5 + 5^2 + 5^3 + ... + 5^2022
2.Tính tổng A = 1^2 + 2^2 + 3^3 + ... + 20^2
3.Tìm X
a) 2^X + 2^X+3 = 5^2
b) (X - 5)^2022 = (X - 5)^2021
c) (2 . X + 1)^3 = 9 . 81
4.Tìm tập hợp các số tự nhiên X, biết rằng 5^2X-1 thỏa mãn điều kiện 100 < 5^2X-1 < 5^6
5.So sánh
a) 3^2N và 2^3N
b)199^20 và 2003^15
5:
a: \(3^{2n}=\left(3^2\right)^n=9^n\)
\(\left(2^{3n}\right)=\left(2^3\right)^n=8^n\)
=>\(3^{2n}>2^{3n}\)
b: \(199^{20}=\left(199^4\right)^5=1568239201^5\)
\(2003^{15}=\left(2003^3\right)^5=8036054027^5\)
mà \(1568239201< 8036054027\)
nên \(199^{20}< 2003^{15}\)
4: \(100< 5^{2x-1}< 5^6\)
mà \(25< 100< 125\)
nên \(125< 5^{2x-1}< 5^6\)
=>3<2x-1<6
=>4<2x<7
=>2<x<7/2
mà x nguyên
nên x=3
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
a ( 3/4 + 1/2 ) x 5/7 =
Tính bằng hai cách:
Cách 1 :
Cách 2 :
b) 5/7 x 13/21 + 2/7 x 13/ 21=
Tính bằng hai cách :
Cách 1 :
Cách 2 :
c) Tính 7/5 + 4/3 + 7/5 + 4/3 bằng hai cách :
Cách 1 : 7/5 + 4/3 + 7/5 + 4/3 = 7/5 x 2 + 4/3 x 2 =
Cách 2 : 7/5 + 4/3 + 7/5 + 4/3 = ( 7/5 + 4/3) x 2 =
a) Cách 1 : (3/4 + 1/2) x 5/7
= 5/4 x 5/7
= 25/28
Cách 2 : (3/4 + 1/2) x 5/7
= 3/4 x 5/7 + 1/2 x 5/7
= 15/28 + 5/14
= 25/28
b) Cách 1 : 5/7 x 13/21 + 2/7 x 13/21
= 65/147 + 26/147
= 13/21
Cách 2 : 5/7 x 13/21 + 2/7 x 13/21
= (5/7 + 2/7) x 13/21
= 1 x 13/21
= 13/21
câu c tự làm
8 /15 :2/3+7/15:2/3 = tính bằng 2 cách nhé các bạn
Cách 1:6/8+4/8+5/7=10/8*5/7=50/56=25/28
Cách 2 :3/4*5/7+1/2*
5/7=15/28+10/28=25/28
Cái này thầy tôi đã chữa yên tâm
Tính :
a) 13/15 + 4/7 - 101/105 b) 2/5 + 3/5 + x 4/9 c) 3/4 x 5/2 x 7/6
d) 1/2 : 1/4 - 2/9 e) 2/3 - 1/4 +2/9 g) 5/2 + 1/3 x 3/2
a: =91/105+60/105-101/105
=50/105=10/21
c: \(\dfrac{3}{4}\cdot\dfrac{5}{2}\cdot\dfrac{7}{6}=\dfrac{3}{6}\cdot\dfrac{7}{2}\cdot\dfrac{5}{4}=\dfrac{1}{2}\cdot\dfrac{7}{2}\cdot\dfrac{5}{4}=\dfrac{35}{16}\)
d: =2-2/9
=18/9-2/9
=16/9
e: =24/36-9/36+8/36
=23/36
g: =5/2+1/2
=3
Tính giá trị các biểu thức sau và viết kết quả dưới dạng bình phương của 1 số
A = 2^5 x (-5)^2 - 8^2 - 7
B = 2^3 x (-4)^2 + (-3)^2 x 3^2 - 40
C= (1/4 - 1/2 - 1) ^3 x (2 - 2/5)^3
D = ( -1/4)^2 : (1/2 - 1/3)
E= 4 x (1/4)^2 + 25 x [(3/4)^3 : (5/4)^3] : (3/2)^3
F = 2^3 + 3 x (1/2)^0 - 1+[(-2)^2 : 1/2] - 8
A = 2⁵.(-5)² - 8² - 7
= 32.25 - 64 - 7
= 729
= 27²
B = 2³.(-4)² + (-3)².3² - 40
= 8.16 + 9.9 - 40
= 169
= 13²
C = (1/4 - 1/2 - 1)³ . (2 - 2/5)³
= (-5/4)³ . (8/5)³
= (-5/4 . 8/5)³
= (-2)³
D = (-1/4)² : (1/2 - 1/3)
= 1/16 : 1/6
= 3/8
E = 4 . (1/4)² + 25 . [(3/4)³ : (5/4)³] : (3/2)³
= 1/4 + 25 . (3/4 . 5/4)³ : (3/2)³
= 1/4 + 25 . (15/16)³ : 27/8
= 1/4 + 25 . 3375/4096 : 27/8
= 1/4 + 84375/4096 : 27/8
= 1/4 + 3125/512
= 3253/512
F = 2³ + 3.(1/2)⁰ - 1 + [(-2)² : 1/2] - 8
= 8 + 3.1 - 1 + (4 : 1/2) - 8
= 8 + 3 - 1 + 8 - 8
= 10
bài 1 : tính : a. 3 2/5 - 1/2 b. 4/5 + 1/5 x 3/4 c. 4 4/9 : 2 2/3 + 3 1/6 d. 3 1/5 + 2 3/5 - 2 4/5
bài 2 :đặt tính rồi tính : 3 2/5 + 2 1/5 b. 7 1/6 : 5 2/3
bài 3 ; điền dấu > , <, =
a. 800 kg 5 g ...8, 005 kg c. 5m 5mm .. 5 ,0005 m
b . 9 ha 4 dam2 . 9 5/100 ha d. 250kg ... 1/5 tấn
giúp mình vs . mình cảm ơn các bạn
Bài 1:
a, 3\(\dfrac{2}{5}\) - \(\dfrac{1}{2}\)
= \(\dfrac{17}{5}\) - \(\dfrac{1}{2}\)
= \(\dfrac{34}{10}\) - \(\dfrac{5}{10}\)
= \(\dfrac{29}{10}\)
b, \(\dfrac{4}{5}\) + \(\dfrac{1}{5}\) x \(\dfrac{3}{4}\)
= \(\dfrac{4\times4}{5\times4}\) + \(\dfrac{1\times3}{5\times4}\)
= \(\dfrac{16}{20}\) + \(\dfrac{3}{20}\)
= \(\dfrac{19}{20}\)
c, 4\(\dfrac{4}{9}\) : 2\(\dfrac{2}{3}\) + 3\(\dfrac{1}{6}\)
= \(\dfrac{40}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{19}{6}\)
= \(\dfrac{5}{3}\) + \(\dfrac{19}{6}\)
= \(\dfrac{10}{6}\) + \(\dfrac{19}{6}\)
= \(\dfrac{29}{6}\)
Bài 2:
3\(\dfrac{2}{5}\) + 2\(\dfrac{1}{5}\)
= \(\dfrac{17}{5}\) + \(\dfrac{11}{5}\)
= \(\dfrac{28}{5}\)
b, 7\(\dfrac{1}{6}\) : 5\(\dfrac{2}{3}\)
= \(\dfrac{43}{6}\) : \(\dfrac{17}{3}\)
= \(\dfrac{43}{34}\)
Bài 3:
a, 800 kg 5g > 8,005 kg
b, 9 ha 4 dam2 < 9\(\dfrac{5}{100}\) ha
c, 5m 5mm > 5,0005 m
d, 250 kg > \(\dfrac{1}{5}\) tấn
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
a)\(\dfrac{2}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}+\dfrac{1}{3}\right).\dfrac{4}{5}=1.\dfrac{4}{5}=\dfrac{4}{5}\)
b)\(\dfrac{2}{3}.\dfrac{4}{5}-\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}-\dfrac{1}{3}\right).\dfrac{4}{5}=\dfrac{1}{3}.\dfrac{4}{5}=\dfrac{4}{15}\)
a) \(\dfrac{2}{3}\times\dfrac{4}{5}+\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{4}{5}\times1=\dfrac{4}{5}\)
b) \(\dfrac{2}{3}\times\dfrac{4}{5}-\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}-\dfrac{1}{3}\right)=\dfrac{4}{5}\times\dfrac{1}{3}=\dfrac{4}{15}\)
c) \(\dfrac{1}{2}:\dfrac{3}{4}+\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}+\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\times\left(\dfrac{1}{2}+\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{2}{3}=\dfrac{8}{9}\)
d) \(\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}-\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{1}{3}=\dfrac{4}{9}\)
c)\(\dfrac{1}{2}:\dfrac{3}{4}+\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}.\dfrac{4}{3}+\dfrac{1}{6}.\dfrac{4}{3}=\left(\dfrac{1}{2}+\dfrac{1}{6}\right).\dfrac{4}{3}=\dfrac{2}{3}.\dfrac{4}{3}=\dfrac{8}{9}\)
d)\(\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}.\dfrac{4}{3}-\dfrac{1}{6}.\dfrac{4}{3}=\left(\dfrac{1}{2}-\dfrac{1}{6}\right).\dfrac{4}{3}=\dfrac{1}{3}.\dfrac{4}{3}=\dfrac{4}{9}\)
Bài 1:thực hiện phép tính(hợp lí nếu có thể):
1, -5/12 x 2/11 + -5/12 x 9/11 + 5/12
2, -3/5 : 7/5 - 3/5 : 7/5 + 2 3/5
3, 1/2+ 3/4 - ( 3/4 - 4/5)
4, 2/3 + 1/3 x ( -4/9 + 5/6)
5, -3/7 x 5/9 + 4/9 x -3/7 + ( - 2022) ^ 0
6,0,75 - ( 2 1/3 + 0,75) + 3 ^ 2 x ( -1/9)
7, 2 6/7 x [(-7/5 - 3/2 : -5/-4) + ( 3/2)^2]
8,2/7 + 5/7 x ( 3/5 - 0,25 ) x ( -2)^2 + 35%
9, 1 13/15 x 0,75 - ( 11/20 + 25%): 1 2/5
10, ( -2,4 + 1/3 ) : 3 1/10 + 75% : 1 1/2
11.5/3 - 5/7 + 5/9 / 10/3 - 10/7 + 10/9
Bài 299: Tính
1) 1/3 x 1/2 x 3/7
2) 5/4 x 1/3 + 1/7
3) 8 x ( 8/9-2/3 )
4) 5/6 x 48/20 x 1/2
5) ( 2/5 + 3/4 + x 8
6) 10 x ( 1/2 - 1/5 )
Trình bày rõ cách làm giúp ạ!!
1) 1/3 x 1/2 x 3/7 = 3/42 = 1/14
2) 5/4 x 1/3 +1/7 = 5/12 + 1/7 = 35/84 + 12/84 = 47/84
3) 8 x ( 8/9 - 2/3 ) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 240/240 = 1
5) ( 2/5 + 3/4 ) + 8 = 23/20 + 8 = 23//20 + 160/20 = 183/20
6) 10 x ( 1/2 - 1/5 ) = 10 x 3/10 = 10/1 x 3/10 = 30/10 = 3