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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
![](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)
b: Ta có: \(\left(x-3\right)^3-\left(x+2\right)\left(x^2-2x+4\right)+9\left(x+2\right)^2\)
\(=x^3-9x^2+27x-27-x^3-8+9x^2+36x+36\)
\(=53x+1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) x - 3/2 = 4/3
x = 4/3 + 3/2
x = 8/6 + 9/6 = 17/6
b) 2/5 * x = 1/3
x = 1/3 : 2/5
x = 1/3 x 5/2 = 5/6
c) x - 4/9 = 3/7 : 9/14
x - 4/9 = 2/3
x = 2/3 + 4/9
x = 6/9 + 4/9 = 10/9
d) 3/5 * x - 1/2 = 1/5
3/5 * x = 1/5 + 1/2 = 7/10
x = 7/10 : 3/5
x = 7/10 * 5/3 = 7/6
a/\(x-\dfrac{3}{2}=\dfrac{4}{3}\)
\(x=\dfrac{4}{3}+\dfrac{3}{2}\)
\(x=\dfrac{17}{6}\)
b/\(\dfrac{2}{5}\times x=\dfrac{1}{3}\)
\(x=\dfrac{1}{3}:\dfrac{2}{5}\)
\(x=\dfrac{5}{6}\)
c/\(x-\dfrac{4}{9}=\dfrac{3}{7}:\dfrac{9}{14}\)
\(x-\dfrac{4}{9}=\dfrac{2}{3}\)
\(x=\dfrac{2}{3}+\dfrac{4}{9}\)
\(x=\dfrac{10}{9}\)
d/\(\dfrac{3}{5}\times x-\dfrac{1}{2}=\dfrac{1}{5}\)
\(\dfrac{3}{5}\times x=\dfrac{1}{5}+\dfrac{1}{2}\)
\(\dfrac{3}{5}\times x=\dfrac{7}{10}\)
\(x=\dfrac{7}{10}:\dfrac{3}{5}\)
\(x=\dfrac{7}{6}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
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
![](https://rs.olm.vn/images/avt/0.png?1311)
1.1 Hình vuông có tối đa 4 góc vậy 4 hình vuông có tối đa 20 góc. S
2.1 hình vuông có tối đa 4 góc vậy 4 hình vuông có tối đa 16 góc. Đ
3. 1 hình vuông có tối thiểu 4 góc vậy 4 hình vuông có tối thiểu 16 góc. Đ
4.1 hình vuông có tối thiểu 1 góc vậy 4 hình vuông có tối thiểu 16 góc. S
Nhiêu đó hết tài năng rồi, mình mới lớp 3 thôi.
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 1/4(x-3)+2=1/5
1/4.(x-3) = 1/5-2
1/4.(x-3) = -9/5
x-3 = (-9/5):1/4
x-3 = -36/5
x = -36/5+3
x= -21/5
![](https://rs.olm.vn/images/avt/0.png?1311)
`a, 3/4 + 1/2 xx 7/2`
`= 3/4 + 7/4`
`=10/4`
`=5/2`
`b, 6/15 - 1/3 : 5/3`
`= 6/15 - 1/3 xx 3/5`
`= 6/15 - 3/15`
`= 3/15`
`=1/5`
`c, x-4/9 = 3/7 : 9/4`
`=> x-4/9= 3/7 xx 4/9`
`=> x-4/9= 12/63`
`=> x-4/9=4/21`
`=> x= 4/21 +4/9`
`=>x= 40/63`
`d, 7/9 xx 3/5 -1/2=1/5`
`->` sao lại bằng có `x` ko vậy ạ?
`a,`
`3/4+1/2 \times 7/2=3/4+7/4=10/4=5/2`
`b,`
`6/15 - 1/3 \div 5/3=6/15-1/5=1/5`
`c,` Tìm x?
`x-4/9=3/7 \div 9/4`
`x-4/9=4/21`
`x=4/21+4/9`
`x=40/63`
`d, 7/9x \times 3/5-1/2=1/5`
`7/9x \times 3/5=1/5+1/2`
`7/9x \times 3/5=7/10`
`7/9x=7/10 \div 3/5`
`7/9x=7/6`
`x=7/6 \div 7/9=3/2`
(x-3/4) = 9/2-3/2
(x-3/4) = 6/2
x = 3+ 3/4
x = 15/4