-1/9.2/19+-1/9.17/19-1 và 8/9
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a) = 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
b) = 1/3 x 4/5 + 1/3 x6/5 + 1/3 x 2 = 1/3(4/5 + 6/5 + 2) = 1/3 x 4 = = 4/3
c) 4/7 x 2/9 + 4/7 x 7/9 + 2/3 = 4/7 x (2/9 + 7/9) + 2/3 = 4/7 x 1 + 2/3 = 26/21
A) 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
B) 1/3 x 4/5 + 1/3 x 6/5 + 1/3 x 2 = 1/3 x(4/5 + 6/5 x 2 ) = 1/3 x 4 = 4/3
c) TƯƠNG TỰ CÂU A VÀ B
* HOKTOT*
NHA
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a, 7/9 và 9/11
b, 1/5, 3/10 và 4/15
c, 3/7, 4/9 và 8/21
d, 7/6 và 6/10
e, 19/10 và 8/9
g, 19/24 và 3/8
Nhìn phân số ở đây cho dễ
a: 7/9=77/99
9/11=63/99
b: 1/5=6/30
3/10=9/30
4/15=8/30
c: 3/7=27/63
4/9=28/63
8/21=24/63
d: 7/6=35/30
6/10=18/30
e: 19/10=171/90
8/9=80/90
g: 19/24=19/24
3/8=9/24
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\(\frac{3^{19}.2^9+5.9^9.2^9}{3^{19}.2^9+9^{10}.2^{10}}\)
\(=\frac{3^{19}.2^9+5.\left(3^2\right)^9.2^9}{3^{19}.2^9+\left(3^2\right)^{10}.2^{10}}\)
\(=\frac{3^{19}.2^9+5.3^{18}.2^9}{3^{19}.2^9+3^{20}.2^{10}}\)
\(=\frac{3^{18}.2^9\left(3+5\right)}{3^{19}.2^9\left(1+6\right)}\)
\(=\frac{8}{3.7}=\frac{8}{21}\)
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\(a,\Rightarrow\left(x-\dfrac{1}{2}\right)^3=\dfrac{1}{27}=\left(\dfrac{1}{3}\right)^3\\ \Rightarrow x-\dfrac{1}{2}=\dfrac{1}{3}\Rightarrow x=\dfrac{5}{6}\\ b,\Rightarrow\left(\dfrac{3}{2}\right)^{2x-1}:\left(\dfrac{3}{2}\right)^9=\left(\dfrac{3}{2}\right)^4\\ \Rightarrow2x-1-9=4\\ \Rightarrow2x=14\Rightarrow x=7\\ c,\Rightarrow2^{x-1}+2^{x+2}=9\cdot2^5\\ \Rightarrow2^{x-1}\left(1+2^3\right)=9\cdot2^5\\ \Rightarrow2^{x-1}\cdot9=9\cdot2^5\\ \Rightarrow2^{x-1}=2^5\Rightarrow x-1=5\Rightarrow x=6\\ d,\Rightarrow\left(2x+1\right)^2=12+69=81\\ \Rightarrow\left[{}\begin{matrix}2x+1=9\\2x+1=-9\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-5\end{matrix}\right.\)
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a,7429-(3125+4297)
=7407-93103+4297)
=7407-7400
7
b,9/8-(17/7-3/7)+7/8
=(9/8 +7/8)-(17/7-3/7)
=2-2
=0
c,tự làm nhé..
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Phương pháp giải:
- Tính giá trị của mỗi vế
- So sánh rồi điền dấu thích hợp vào chỗ trống.
Lời giải chi tiết:
19 + 7 < 19 + 9 17 + 7 < 17 + 9
17 + 9 = 19 + 7 37 + 15 < 55 − 1
38 − 8 = 23 + 7 28 − 3 > 17 + 6