x/30+1/2+x/40=5+1/6
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
CM
24 tháng 1 2017
Hướng dẫn giải:
a) 3 x (20 – 5)
Cách 1:
3 x (20 – 5) = 3 x 15 = 45
Cách 2:
3 x (20 – 5) = 3 x 20 – 3 x 5 = 60 – 15 = 45
b) 20 x (40 – 1)
Cách 1:
20 x (40 – 1) = 20 x 39 = 780
Cách 2:
20 x (40 – 1) = 20 x 40 – 20 x 1 = 800 – 20 = 780
LM
Lê Minh Vũ
VIP
15 tháng 6 2023
3 x 15 + 21 x 15 + 85 x 5
= 45 + 315 + 425
= 785
15 - 30 + 40
= 25
21 + 19 - 50 + 10
= 0
\(\dfrac{1}{5}-\dfrac{1}{4}+2\)
\(=-\dfrac{1}{20}+2\)
\(=\dfrac{39}{20}\)
\(\left(\dfrac{1}{4}+\dfrac{1}{6}\right)\times\left(\dfrac{1}{2}-\dfrac{1}{4}\right)\)
\(=\dfrac{5}{12}\times\dfrac{1}{4}\)
\(=\dfrac{5}{12}\times\dfrac{3}{12}\)
\(=\dfrac{5}{48}\)
\(\dfrac{1}{10}+\dfrac{1}{5}-\dfrac{3}{4}\)
\(=-\dfrac{9}{20}\)
BD
15 tháng 6 2023
\(3\times15+21\times15+85\times5\\ =15\times\left(3+21\right)+425\\ =15\times24+425\\ =360+425\\ =785\)
\(15-30+40\\ =\left(15+40\right)-30\\ =55-30\\ =25\)
\(21+19-50+10\\ =\left(21+19\right)-\left(50-10\right)\\ =40-40\\ =0\)
\(\dfrac{1}{5}-\dfrac{1}{4}+2\)
\(=\dfrac{4}{20}-\dfrac{5}{20}+\dfrac{40}{20}\)
\(=\dfrac{\left(4+40\right)}{20}-\dfrac{5}{20}\)
\(=\dfrac{44}{20}-\dfrac{5}{20}\)
\(=\dfrac{39}{20}\)
\(\left(\dfrac{1}{4}+\dfrac{1}{6}\right)\times\left(\dfrac{1}{2}-\dfrac{1}{4}\right)\)
\(=\dfrac{5}{12}\times\dfrac{1}{4}\)
\(=\dfrac{5}{48}\)
\(\dfrac{1}{10}+\dfrac{1}{5}-\dfrac{3}{4}\)
\(=\dfrac{2}{20}+\dfrac{4}{20}-\dfrac{15}{20}\)
\(=\dfrac{6}{20}-\dfrac{15}{20}\)
\(=-\dfrac{9}{20}\)
27 tháng 5 2017
B)
( x + 4/3 ) * 7/4 = 5 - 7/6
( x + 4/3) * 7/4 = 5/1 - 7/6
( x + 4/3) * 7/4 = 30/6 - 7/6
( x + 4/3) * 7/4 = 23/6
( x + 4/3) = 23/6 : 7/4
( x+ 4/3) = 23/6 . 4/7
( x+ 4/3) = 46/21
x = 46/21 - 4/3
x = 46/21 - 28/21
x = 18/21 = 6/7
Tk vs kb hộ mk nha! thank u
DK
27 tháng 5 2017
may cau khac ko kho lam dau chi co cau d thoi.
(100%-50%+40%):x=18%+30%:x
90%:x=18%+30%:x
18%=90%:x-30%:x
18%=60%:x
X=60%:18%
x=..................................................................................................
xong roi do a cho minh nhe
KH
28 tháng 2 2018
a) \(x=\dfrac{1}{4}+\dfrac{2}{13}\)
\(x=\dfrac{13}{52}+\dfrac{8}{52}\)
⇒ \(x=\dfrac{21}{52}\)
b) \(\dfrac{x}{3}=\dfrac{2}{3}+\dfrac{-1}{7}\)
\(\dfrac{x}{3}=\dfrac{14}{21}+\dfrac{-3}{21}\)
\(\dfrac{x}{3}=\dfrac{11}{21}\)
⇒ \(x=\dfrac{11.3}{21}=\dfrac{33}{21}\)
⇒ \(x=\dfrac{11}{7}\)
c) \(\dfrac{-8}{3}+\dfrac{1}{3}< x< \dfrac{-2}{7}+\dfrac{-5}{7}\)
\(\dfrac{-17}{7}< x< -1\)
⇒ \(-17< x< -7\)
⇒ \(x\in\left\{-16;-15,....;-6\right\}\)
d) \(\dfrac{1}{6}+\dfrac{2}{5}\)
\(=\dfrac{5}{30}+\dfrac{12}{30}\)
\(=\dfrac{17}{30}\)
e) \(\dfrac{3}{5}+\dfrac{-7}{4}\)
\(=\dfrac{12}{20}+\dfrac{-35}{20}\)
\(=\dfrac{-23}{20}\)
f) \(\dfrac{4}{13}+\dfrac{-12}{30}\)
\(=\dfrac{4}{13}+\dfrac{-2}{5}\)
\(=\dfrac{20}{65}+\dfrac{-26}{65}\)
\(=\dfrac{-6}{65}\)
g) \(\dfrac{-3}{29}+\dfrac{16}{58}\)
\(=\dfrac{-6}{58}+\dfrac{16}{58}\)
\(=\dfrac{10}{58}\)
h) \(\dfrac{8}{40}+\dfrac{-36}{45}\)
\(=\dfrac{1}{5}+\dfrac{-4}{5}\)
\(=\dfrac{-3}{5}\)
j) \(\dfrac{-8}{18}+\dfrac{15}{27}\)
\(=\dfrac{-2}{9}+\dfrac{5}{9}\)
\(=\dfrac{3}{9}\)
\(=\dfrac{1}{3}\)
21 tháng 11 2017
a)
\(P=\dfrac{x^{10}-x^8+x^6-x^4+x^2-1}{x^4-1}\)
\(=\dfrac{x^8\left(x^2-1\right)+x^4\left(x^2-1\right)+\left(x^2-1\right)}{\left(x^2-1\right)\left(x^2+1\right)}\)
\(=\dfrac{\left(x^2-1\right)\left(x^8+x^4+1\right)}{\left(x^2-1\right)\left(x^2+1\right)}\)
\(=\dfrac{x^8+x^4+1}{x^2+1}\)
b)
\(Q=\dfrac{x^{40}+x^{30}+x^{20}+x^{10}+1}{x^{45}+x^{40}+x^{35}+...+x^{10}+x^5+1}\)
\(=\dfrac{x^{40}+x^{30}+x^{20}+x^{10}+1}{\left(x^{45}+x^{35}+...+x^5\right)+\left(x^{40}+x^{30}+...+1\right)}\)
\(=\dfrac{x^{40}+x^{30}+x^{20}+x^{10}+1}{x^5\left(x^{40}+x^{30}+...+1\right)+\left(x^{40}+x^{30}+...+1\right)}\)
\(=\dfrac{x^{40}+x^{30}+x^{20}+x^{10}+1}{\left(x^{40}+x^{30}+...+1\right)\left(x^5+1\right)}\)
\(=\dfrac{1}{\left(x^5+1\right)}\)
21 tháng 11 2017
cái câu b dòng cuối mẫu số đóng mở ngoặc chi cho mệt ei =.=
PT
2
CM
3 tháng 6 2019
Học sinh nhẩm và ghi kết quả như sau:
6 x 4 = 24
6 x 2 = 12
6 x 5 = 30
6 x 1 = 6
24 : 6 = 4
12 : 6 = 2
30 : 6 = 5
6 : 6 = 1
24 : 4 = 6
12 : 2 = 6
30 : 5 = 6
6 : 1 = 6
(có thể nêu nhận xét: lấy tích chia cho một thừa số được thừa số kia)
YV
1
8 tháng 2 2017
a) \(3\times\left(-2\right)+4\times6-2^2+\left(-2\right)^2\)
\(=\left(-6\right)+24-4+4\)
\(=18-4+4\)
\(=14+4\)
\(=18\)
b) \(-25-40+3\times6\)
\(=-25-40+18\)
\(=-65+18\)
\(=-47\)
c) \(30\times\left(-10\right)-30\times90\)
\(=\left(-300\right)-2700\)
\(=-3000\)
Chúc bạn học tốt
18 tháng 7 2017
\(x^6:x^3=125\)
\(x^3=125\)
\(x^3=5^3\)
\(\Rightarrow x=5\)
b, \(3.2^x-3=45\)
\(3.2^x=45+3\)
\(3.2^x=48\)
\(2^x=48:3\)
\(2^x=16\)
\(2^x=2^4\)
\(\Rightarrow x=4\)
c, \(1500:\left[\left(30+40\right):x\right]=30\)
\(1500:\left[70:x\right]=30\)
\(70:x=1500:30\)
\(70:x=50\)
\(x=70:50\)
\(x=\frac{70}{50}\)
\(x=\frac{7}{5}\)
d, \(720:\left[41-\left(2x-5\right)\right]=2^3.5\)
\(720:\left[41-\left(2x-5\right)\right]=8.5\)
\(720:\left[41-\left(2x-5\right)\right]=40\)
\(41-\left(2x-5\right)=720:40\)
\(41-\left(2x-5\right)=18\)
\(2x-5=41-18\)
\(2x-5=23\)
\(2x=23+5\)
\(2x=28\)
\(x=28:2\)
\(x=14\)
bạn thử lại nhé
18 tháng 7 2017
Ta có x20=x1
=> x=0 hoặc x=1
x6:x3=x6-3=x3=125
=>x3=53
=> x=5
Ta có
4x3+12=120
=>4x3=108
=>x3=27
=>x=3
Ta có
3.2x-3=45
=>3(2x-1)=45
=>2x-1=15
=>2x=16
=> x=2 hoặc x=-2
Ta có 1500:[(30+40):x]=30
=>70:x=50
=> x=7/5
Ta có
720:[41-(2x-5)]=23.5
=>41-(2x-5)=720:40=18
=> 2x-5=23
=>x=(23+5):2=14
KL
O
31 tháng 3 2022
Bài 1
\(\dfrac{1}{2}+\dfrac{7}{10}=\dfrac{5}{10}+\dfrac{7}{10}=\dfrac{12}{10}=\dfrac{6}{5}\)
\(\dfrac{8}{15}\times\dfrac{5}{12}=\dfrac{40}{180}=\dfrac{2}{9}\)
Baì 2
\(30\times\dfrac{5}{3}=50\)
\(\dfrac{6}{5}\times\dfrac{5}{3}=2\)
\(\dfrac{12}{40}\times\dfrac{5}{3}=\dfrac{1}{2}\)
lớp 8 ???
\(\dfrac{x}{30}+\dfrac{1}{2}+\dfrac{x}{40}=5+\dfrac{1}{6}\)
\(\Leftrightarrow\dfrac{x}{30}+\dfrac{x}{40}=\dfrac{14}{3}\)
\(\Leftrightarrow\dfrac{4x+3x}{120}=\dfrac{560}{120}\)
\(\Leftrightarrow7x=560\)
\(\Leftrightarrow x=80\)