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a, 48.84
= (22)8.(23)4
= 216.212
= 228
b, 415.515
= (4.5)15
= 2015
c, 210.15 + 210.85
= 210.(15 + 85)
= 210.100
=210.(2.5)2
= 212.52
d, 33.92
= 33 . (32)2
= 33.34
= 37
e, 512.7 - 511.10
= 511.(5.7 - 10)
= 511.25
=511.52
=513
f, \(x^1\).\(x^2\).\(x^3\)....\(x^{100}\)
= \(x^{1+2+3+...+100}\)
= \(x^{\left(1+100\right).100:2}\)
= \(x^{5050}\)
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a,-3/5.2/7+-3/7.3/5+-3/7
=-3/7.2/5+(-3/7).3/5+(-3/7)
=-3/7(2/5+3/5+1)
=-3/7.2
=-6/7
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c) \(\frac{3\cdot7-3\cdot19}{3\cdot4}=\frac{3\left(7-19\right)}{3\cdot4}=\frac{3\cdot\left(-12\right)}{3\cdot4}=\frac{3\cdot4\cdot\left(-3\right)}{3\cdot4}=-3\)
Vậy \(\frac{3\cdot7-3\cdot19}{3\cdot4}=-3\)
d,\(\frac{2^3\cdot9^4-2^4\cdot3^7}{2^4\cdot3^7}=\frac{2^3\cdot\left(3^2\right)^4-2^4\cdot3^7}{2^4\cdot3^7}=\frac{2^3\cdot3^8-2^4\cdot3^7}{2^2\cdot3^7}=\frac{2^3\cdot3^7\left(3-2\right)}{2^2\cdot3^7}=2\)
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G=\(\frac{3}{2.5}+\frac{3}{5.7}+\frac{3}{7.9}+...+\frac{3}{2015.2017}\)
G=\(3.\left(\frac{1}{2.5}+\frac{1}{5.7}+\frac{1}{7.9}+...+\frac{1}{2015.2017}\right)\)
G=\(3.\left(\frac{1}{2}.\frac{1}{5}+\frac{1}{5}.\frac{1}{7}+\frac{1}{7}.\frac{1}{9}+...+\frac{1}{2013}.\frac{1}{2015}+\frac{1}{2015}.\frac{1}{2017}\right)\)
G=\(3.\left(\frac{1}{2}+\frac{1}{2017}\right)\)
G=1.5
Anh ko bik có đúng ko nữa lâu quá rồi. Em thông cảm nhé
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\(\left[3\cdot\left(x+2\right):7\right]\cdot4=120\)
\(\Rightarrow3\left(x+2\right):7=30\)
\(\Rightarrow3\left(x+2\right)=210\)
\(\Rightarrow x+2=70\)
\(\Rightarrow x=68\)
Vậy x=68
[ 3 . ( x + 2 ) : 7 ] . 4 = 120
3 . ( x + 2 ) : 7 = 30
3 . ( x + 2 ) = 210
x + 2 = 70
x = 68
Nhớ li ke mk nha
![](https://rs.olm.vn/images/avt/0.png?1311)
( 3 x ( x + 2 ) : 7 ) x 4 = 120
( 3 x ( x + 2 ) : 7 ) = 120 : 4
3 x ( x + 2 ) : 7 = 30
3 x ( x + 2 ) = 30 x 7
3 x ( x +2 ) = 210
x + 2 = 210 : 3
x + 2 = 70
x = 68
Bài làm
[3.9(x+2):7]:4=120
[3.9(x+2):7] = 120.4
3.9(x+2):7 = 480