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a, 3 - 2x = 3 . (5 - x) + 4
3 - 2x = 15 - 3x + 4
-2x + 3x = 15 + 4 - 3
x = 16
b, 4 - (7x + 2017) = 6 . (5 - x) - 2017
4 - 7x - 2017 = 30 - 6x - 2017
-7x + 6x = 30 - 2017 - 4 + 2017
-x = 26
x = -26
c, 15 - x . (x + 1) = 4 - x^2 + 2x
15 - x^2 - x = 4 - x^2 + 2x
-x^2 - x + x^2 - 2x = 4 - 15
-3x = -11
x = 11/3
d, -4 . (x - 5) + 2016 = 3 . (8 - x) - (2x - 2016)
-4x + 20 + 2016 = 24 - 3x - 2x + 2016
-4x + 3x +2x = 24 + 2016 - 20 - 2016
x = 4
đúng 100%
( - 63 ) . 39 + 37 . ( - 39 ) Chúc bạn học tốt
= - 63 . 39 + ( - 39 ) . 37
= - 63 .39 - 39 .37
= 39 . ( -63 - 37 )
= 39 . ( - 100 )
= - 3900
- 63 ) . 39 + 37 . ( - 39 )
= - 63 . 39 + ( - 39 ) . 37
= - 63 .39 - 39 .37
= 39 . ( -63 - 37 )
= 39 . ( - 100 ) = - 3900
a là x và y thuộc nhóm rỗng
b thì =-1+-1+-1+...+-1+2017=-1008+2017=1009
c là vì 4S+1 là 5^2016 chia hết cho 5^2016
vì 6(5+5^2+...+5^2014) chia hết cho 6 và bằng S
\(\frac{x+5}{2013}+\frac{x+7}{2011}=\frac{x+1}{2017}+\frac{2}{2016}\)
\(\Leftrightarrow\left(\frac{x+5}{2013}+1\right)+\left(\frac{x+7}{2011}+1\right)=\left(\frac{x+1}{2017}+1\right)+\left(\frac{x+2}{2016}+1\right)\)
\(\Leftrightarrow\frac{x+2018}{2013}+\frac{x+2018}{2011}=\frac{x+2018}{2017}+\frac{x+2018}{2016}\)
\(\Leftrightarrow\frac{x+2018}{2013}+\frac{x+2018}{2011}-\frac{x+2018}{2017}-\frac{x+2018}{2016}=0\)
\(\Leftrightarrow\left(x+2018\right)\left(\frac{1}{2013}+\frac{1}{2011}-\frac{1}{2017}-\frac{1}{2016}\right)=0\)
Mà \(\frac{1}{2013}+\frac{1}{2011}-\frac{1}{2017}-\frac{1}{2016}\ne0\)
\(\Leftrightarrow x+2018=0\)
\(\Leftrightarrow x=-2018\)
Vậy ...
\(\frac{x+5}{2013}+\frac{x+7}{2011}=\frac{x+1}{2017}+\frac{2}{2016}\)
\(\Leftrightarrow\left(\frac{x+5}{2013}+1\right)+\left(\frac{x+7}{2011}+1\right)=\left(\frac{x+1}{2017}+1\right)+\left(\frac{x+2}{2016}+1\right)\)
\(\Leftrightarrow\frac{x+2018}{2013}+\frac{x+2018}{2011}=\frac{x+2018}{2017}+\frac{x+2018}{2016}\)
\(\Leftrightarrow\frac{x+2018}{2013}+\frac{x+2018}{2011}-\frac{x+2018}{2017}-\frac{x+2018}{2016}=0\)
\(\Leftrightarrow\left(x+2018\right)\left(\frac{1}{2013}+\frac{1}{2011}-\frac{1}{2017}-\frac{1}{2016}\right)=0\)
Mà \(\frac{1}{2013}+\frac{1}{2011}-\frac{1}{2017}-\frac{1}{2016}\ne0\)
\(\Leftrightarrow x+2018=0\)
\(\Leftrightarrow x=-2018\)
Vậy \(x=-2018\)
3/5.8 + 3/8.11 + ...+3/2016.2019
= 3 . ( 1/5 - 1/8 + 1/8 - 1/11 + ...+ 1/2016 - 1/2019)
= 3 . (1/5 - 1/2019)
= 3 . 2014/10095
= 2014/3365
D. Tìm x thuộc Z biết
x+(x+1)+(x+2)+....+2016+2017=2017
=> ( x + x + x + ..+ x ) + ( 1 + 2 + 3+...+2016 + 2017 ) = 2017
<=> 2017x + 2035153 = 2017
=> 2017x = -2033136
=> x = -1008
Vậy ...
cảm ơn bạn nhưng bạn có biết những câu hỏi còn lại ko
\(x^{2016}=x^{2017}\\ \Leftrightarrow x^{2016}-x^{2017}=0\\ \Leftrightarrow x^{2016}\left(1-x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x^{2016}=0\\1-x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)
Vậy S = {0;1}
5^x=5^2019:(5^2013-100.5^2010)
=> 5x=52019:(52010.(53-100))
=>5x=52019:(52010.(125-100))
=>5x=52019:(52010.25)
=>5x=52019:52012
=>5x=57
=> x=7