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(2+x)+(4+x)+...+(52+x)=780
=>(x+x+...+x)+(2+4+...+52)=780
=>26x+702=780
=>26x=78
=>x=3
=>(2+4+...+52)+(x+x+...+x)=780 (26 số hạng x)
=>(52+2).26/2+26x=780
=>702+26x=780
=>26x=780-702
=>26x=78
=>x=78:26
=>x=3
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\(a,\Leftrightarrow x^3=\dfrac{20}{3}\Leftrightarrow x=\sqrt[3]{\dfrac{20}{3}}\\ b,\Leftrightarrow x-1=9\Leftrightarrow x=10\\ c,\Leftrightarrow\left[{}\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\\ d,\Leftrightarrow2x+1=5\Leftrightarrow x=2\\ e,\Leftrightarrow2x-4=4\Leftrightarrow x=4\)
Câu a) xem lại đề giùm nhé em
b) \(\left(x-1\right)^3=9^3\)
\(x-1=9\)
\(x=10\)
Vậy \(x=10\)
c) \(\left(x-1\right)^2=25\)
\(x-1=5\) hoặc \(x-1=-5\)
* \(x-1=5\)
\(x=6\)
* \(x-1=-5\)
\(x=-4\)
Vậy \(x=-4\); \(x=6\)
d) \(\left(2x+1\right)^3=125\)
\(\left(2x+1\right)^3=5^3\)
\(2x+1=5\)
\(2x=4\)
\(x=2\)
Vậy \(x=2\)
e) Sửa đề: \(\left(2x+4\right)^3=64\)
\(\left(2x+4\right)^3=4^3\)
\(2x+4=4\)
\(2x=0\)
\(x=0\)
Vậy \(x=0\)
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6\(^2\)+ 64 : ( x - 1 ) = 52
36 + 64 : ( x - 1 ) =52
64 ; ( x - 1 ) =64 : 52
x - 1 = \(\frac{16}{13}\)
x = \(\frac{16}{13}\)+1
x = \(\frac{29}{13}\)
HT
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`52 -4(x- 5) = 40`
`4(x-5) = 52-40 =12`
`x-5 = 12/4=3`
`x=3+5=8`
Vậy `x=8`
x=8