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![](https://rs.olm.vn/images/avt/0.png?1311)
\(x\div\frac{1}{2}+x\div\frac{1}{4}+x\div\frac{1}{8}+x=960\)
\(x\times2+x\times4+x\times8+x=960\)
\(x\times\left(2+4+8+1\right)=960\)
\(x\times15=960\)
\(x=960\div15\)
\(x=64\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Câu 1)
1/5*x=4/6
x=4/6/1/5
x=10/3
Câu 3)x/6*5/8=5/12
x/6=5/12/5/8
x/6=2/3
x/6=4/6
Vây x=4
Câu 3)
5/9/3/x=5/27
3/x=5/9/5/27
3/x=3
Vây x=1
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a) \(x.\dfrac{3}{4}=\dfrac{9}{14}\)
\(\Rightarrow x=\dfrac{9}{14}:\dfrac{3}{4}\)
\(\Rightarrow x=\dfrac{6}{7}\)
b) \(x:\dfrac{5}{9}=\dfrac{3}{10}\)
\(\Rightarrow x=\dfrac{3}{10}.\dfrac{5}{9}\)
\(\Rightarrow x=\dfrac{1}{6}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1/2 + 4/3 = 3/6 + 8/6 = 11/6
4/5 + 3/4 : 2/3 = 4/5 + 3/4 * 3/2 = 4/5 + 9/8 = 32/40 + 45/40 = 77/40
7/2 - 4/3 * 1/6 = 7/2 - 2/9 = 63/18 - 4/18 = 59/18
4/5 * 4/7 : 2/3 = 16/35 : 2/3 = 16/35 * 3/2 = 24/35
1/4 : 5/3 + 1/6 = 1/4 * 3/5 + 1/6 = 3/20 + 1/6 = 9/60 + 10/60 = 19/60
3 - 4/5 : 1/3 = 3 - 4/5 * 3/1 = 3 - 12/5 = 15/5 - 12/5 = 3/5
5/9 * 2/7 - 3/7 = 10/63 - 3/7 = 10/63 - 27/63 = -17/63
![](https://rs.olm.vn/images/avt/0.png?1311)
Kết quả thôi được ko bạn ?
\(\left(x+1\right)\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)\left(x+6\right)+\left(x+7\right)+\left(x+8\right)+\left(x+9\right)\)\(\left(x+10\right)=2015\)
\(x=196\)
\(\Leftrightarrow196\)
Em học tốt nhé
(x+1)+(x+2)+(x+3)+(x+4)+(x+5)+(x+7)+(x+8+(x+9)+(x+10)=2015
x.10 +(1+2+3+...+10) =2015
X.10 +(10+1).5 =2015
X.10 +55 =2015
X.10 =2015-55
X.10 =1960
X =1960:10
X =196.
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 1/2x(3/4+2/5)
1/2x23/20
23/40
b) 3/4:(8/9+16/3)
3/4:56/9
27/224
c) 1/5:1/10-1/3
2-1/3
5/3
d) 3/4x(20/9-8/15)
3/4x76/45
19/15
e) 1/7:5/14-3/2
=2/5-3/2
-11/10 ( Chị nghĩ lớp 4 chưa học đến số âm nên em xem lại đề nhé)
g) 3/2x(11/6-5/12)
3/2x17/12
17/8
a)\(\frac{1}{2}x\left(\frac{3}{4}+\frac{2}{5}\right)\)
\(=\frac{1}{2}x\left(\frac{15}{20}+\frac{8}{20}\right)\)
\(=\frac{1}{2}x\frac{23}{20}\)
\(=\frac{23}{40}\)
b)\(\frac{3}{4}:\left(\frac{8}{9}+\frac{16}{3}\right)\)
\(=\frac{3}{4}:\left(\frac{8}{9}+\frac{48}{9}\right)\)
\(=\frac{3}{4}:\frac{56}{9}\)
\(=\frac{3}{4}x\frac{9}{56}\)
\(=\frac{27}{224}\)
c) \(\frac{1}{5}:\frac{1}{10}-\frac{1}{3}\)
\(=\frac{1}{5}x10-\frac{1}{3}\)
\(=2-\frac{1}{3}\)
\(=\frac{6}{3}-\frac{1}{3}=\frac{5}{3}\)
d) \(\frac{3}{4}x\left(\frac{20}{9}-\frac{8}{15}\right)\)
\(=\frac{3}{4}x\left(\frac{100}{45}-\frac{24}{45}\right)\)
\(=\frac{3}{4}x\frac{76}{45}\)
\(=\frac{19}{5}\)
e) \(\frac{1}{7}:\frac{5}{14}-\frac{3}{2}\)
\(=\frac{1}{7}x\frac{14}{5}-\frac{3}{2}\)
\(=\frac{2}{5}-\frac{3}{2}\)
\(=\frac{4}{10}-\frac{15}{10}\)
\(=\frac{-11}{10}\)
g) \(\frac{3}{2}x\left(\frac{11}{6}-\frac{5}{12}\right)\)
\(=\frac{3}{2}x\left(\frac{22}{12}-\frac{5}{12}\right)\)
\(=\frac{3}{2}x\frac{17}{12}\)
=\(=\frac{17}{8}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
(x + 3) + (x + 7) + (x + 11) + ... + (x + 79) = 860
=> x + 3 + x + 7 + x + 11 + ... + x + 79 = 860
=> (x + x + x + ... + x) + (3 + 7 + 11 + ... + 79) = 860
=> 20x + (79 + 3).20 : 2 = 860
=> 20x + 82.20 : 2 = 860
=> 20x + 82.10 = 860
=> 20x + 820 = 860
=> 20x = 40
=> x = 2
vậy_
#)Giải :
\(\left(x+3\right)+\left(x+7\right)+...+\left(x+79\right)=860\)
\(\left(x+x+...+x\right)+\left(3+7+...+79\right)=860\)(trong mỗi ngoặc có 20 số hạng)
\(x\times20+\frac{\left(79+3\right)\times20}{2}=860\)
\(x\times20+820=860\)
\(x\times20=860-820\)
\(x\times20=40\)
\(x=40\div20\)
\(x=2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
bài 4:so sánh
5/2 lớn hơn 3/7
4/3 lớn hơn,3/2 lớn hơn
bài 6:rút gọn các phân số sau:
3/9=1/3 9/12=3/4 8/18=4/9 60/36=10/6 17/34=1/2 17/51=1/3 35/100=7/20 25/100=1/4 8/1000=1/125 24/30=4/5 18/54=1/3 72/42=12/7
đay nhé mk chưa làm hết đc bn viết liền quá mk nhìn khó mà mk hỏi bài 7 là nhân hay cộng vậy?
\(x\times2+x\times3+x\times4+x\times5+x\times6-x\times9=9999\)
\(x\times\left(2+3+4+5+6-9\right)=9999\)
\(x\times11=9999\)
\(x=9999\div11\)
\(x=909\)