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bài 1 :
a)\(2,5.16,27.4+7,3=\left(2,5.4\right).16,27+7,3=10.16,27+7,3\)
\(=162,7+7,3=170\)
b) \(\frac{2}{3}+\frac{3}{4}-\frac{5}{6}=\left(\frac{2}{3}-\frac{5}{6}\right)+\frac{3}{4}=\frac{-1}{6}+\frac{3}{4}=\frac{7}{12}\)
c) \(17,6-5,3+16,8-7,6+15,3-6,8\)
\(=\left(17,6-7,6\right)+\left(-5,3+15,3\right)+\left(16,8-6,8\right)\)
\(=10+10+10=30\)
d)\(\frac{38}{11}+\left(13,16+\frac{6}{11}\right)=\frac{38}{11}+13,16+\frac{6}{11}\)
\(=\left(\frac{38}{11}+\frac{6}{11}\right)+13,16=4+13,16=17,16\)
\(2,45.46+8.0,75+54.2,45+0,5.8\\ =\left[2,45.46+54.2,45\right]\)
\(+\left[8.0,75+0,5.8\right]=\left[2,45.\left(46+54\right)\right]+\left[8.\left(0,75+0,5\right)\right]\)
\(=\left(2,45.100\right)+\left(8.1,25\right)=245+10=255\)
bài 2 :
a) .....
b) \(1-\left(12,5+x-4,25\right):21,75=0\)
\(\Rightarrow1-\left(12,5+x-4,25\right)=21,75\)
\(\Rightarrow12,5+x-4,25=-20,75\\ \Rightarrow12,5+x=-16,5\)
\(\Rightarrow x=-29\)
cậu có thể tham khảo bài làm trên đây ạ, mn ai thấy đúng thì cho mk xin 1 t.i.c.k đúng ạ ,thank nhiều
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Bài 2:
1) Ta có: \(\left(3x-2\right)^2+27=76\)
\(\Leftrightarrow\left(3x-2\right)^2=49\)
\(\Leftrightarrow\left[{}\begin{matrix}3x-2=7\\3x-2=-7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}3x=9\\3x=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\frac{5}{3}\end{matrix}\right.\)
Vậy: \(x\in\left\{3;\frac{-5}{3}\right\}\)
2) Ta có: \(2^x-15=17\)
\(\Leftrightarrow2^x=32\)
hay x=5
Vậy: x=5
3) Ta có: \(2^x\cdot4=128\)
\(\Leftrightarrow2^x=32\)
hay x=5
Vậy: x=5
4) Ta có: \(8^x+9=10\)
\(\Leftrightarrow8^x=1\)
hay x=0
Vậy: x=0
5) Ta có: \(2^{x-2}=1\)
\(\Leftrightarrow x-2=0\)
hay x=2
Vậy: x=2
6) Ta có: \(3^x+4^2=5^2\)
\(\Leftrightarrow3^x=5^2-4^2=25-16=9\)
hay x=2
Vậy: x=2
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(19,96+4,19-24,15:\left(x:\frac{1}{4}-\frac{1}{4}\right)=23,15\)
\(24,15-24,15:\left(x:\frac{1}{4}-\frac{1}{4}\right)=23,15\)
\(24,15:\left(x:\frac{1}{4}-\frac{1}{4}\right)=1\)
\(x:\frac{1}{4}-\frac{1}{4}=24,15\)
\(4x=24,4\)
\(x=6,1\)
\(\text{Bài này cx đơn giản thôi!}\)
\(4.19-24.15:\left(x:\frac{1}{4}-\frac{1}{4}\right)=23.15-19.96\)
\(4.19-24.15:\left(x:\frac{1}{4}-\frac{1}{4}\right)=3.19\)
\(24.15:\left(x:\frac{1}{4}-\frac{1}{4}\right)=4.19-3.19\)
\(24.15:\left(x:\frac{1}{4}-\frac{1}{4}\right)=1\)
\(x:\frac{1}{4}-\frac{1}{4}=24.15:1\)
\(x:\frac{1}{4}-\frac{1}{4}=24.15\)
\(x:\frac{1}{4}=24.15+\frac{1}{4}\)
\(x:\frac{1}{4}=24.4\)
\(x=24.4.\frac{1}{4}\)
\(x=6.1\)
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a) \(\left( { - 2,5} \right) + \left( { - 0,25} \right) = - \left( {2,5 + 0,25} \right)\)\( = - 2,75\)
b) \(\left( { - 1,4} \right) + 2,1 = 2,1 - 1,4 = 0,7\)
c) \(3,2-5,7 = -(5,7-3,2)=-2,5\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 23=8
24=16
25=32
26=64
27 = 128
28= 256
29= 512
210= 1024
b,32 =9
33=27
34=81
35=243
c,42=16
43=64
44=256
=-5,2-0,99+6,31
=-6,19+6,31
=0,12
-5,2 - (4,19 - 3,2) + (3,81 + 2,5)
= -5,2 - 4,19 + 3,2 + 6,31
= (-5,2 + 3,2) - 4,19 + 6,31
= -2 + 2,12
= 0,12