tìm x biết: (3x-7)2015=(3x-7)2017
Tìm x, biết: \(\left(3x-7\right)^{2015}\)=\(\left(3x-7\right)^{2017}\)
(3x - 7)2015 = (3x - 7)2017
(3x - 7)2017 - (3x - 7)2015 = 0
(3x - 7)2017[(3x - 7)2 - 1] = 0
=> (3x - 7)2017 = 0 hoặc (3x - 7)2 = 1
=> 3x - 7 = 0 hoặc 3x - 7 = ± 1
=> x = 7/3 hoặc x = { 8/3 ; 2 }
Vậy x = { 2; 7/3; 8/3 }
\(y\left(y^2-1\right)=0\Leftrightarrow\orbr{\begin{cases}y=0\\y^2-1=0\end{cases}}\)
(3x - 7)^2015 = (3x - 7)^2017
(3x - 7)^2017 - (3x - 7)^2015 = 0
(3x - 7)^2017 [(3x - 7)^2 - 1] = 0
=> (3x - 7)^2017 = 0 hoặc (3x - 7)^2 = 1
=> 3x - 7 = 0 hoặc 3x - 7 = ± 1
=> x = 7/3 hoặc x = { 8/3 ; 2 }
Vậy x = { 2; 7/3; 8/3 }
Tìm x biết (3x+7)2015=(3x+7)2016
Tìm x biết:
1) x (x-2016) + 2015 (2016-x) = 0
2) -5x (x-15) + (15-x) = 0
3) 3x (3x-7) - (7-3x) =0
1) x (x-2016) + 2015 (2016-x) = 0
x (x-2016) - 2015 (x- 2016) = 0
(x-2015)(x-2016) =0
\(\Rightarrow\orbr{\begin{cases}x-2015=0\\x-2016=0\end{cases}\Rightarrow\orbr{\begin{cases}x=2015\\x=2016\end{cases}}}\)
Vậy x= 2015; 2016
2) -5x (x-15) + (15-x) = 0
-5x (x-15) - (x-15) =0
(-5x -1) (x-15) =0
\(\Rightarrow\orbr{\begin{cases}-5x-1=0\\x-15=0\end{cases}\Rightarrow\orbr{\begin{cases}-5x=1\\x=15\end{cases}\Rightarrow}\orbr{\begin{cases}x=-\frac{1}{5}\\x=15\end{cases}}}\)
Vậy x= -1/5; 15
3) 3x (3x-7) - (7-3x) =0
3x(3x-7) + (3x -7) =0
(3x+1) (3x-7) =0
\(\Rightarrow\orbr{\begin{cases}3x+1=0\\3x-7=0\end{cases}\Rightarrow\orbr{\begin{cases}3x=-1\\3x=7\end{cases}\Rightarrow}\orbr{\begin{cases}x=-\frac{1}{3}\\x=\frac{7}{3}\end{cases}}}\)
Vậy x= -1/3 ; 7/3
Tìm x biết : (3x - 7)2015 = (3x - 7)2017
Ai biết thì chỉ giúp mình với.Gấp lắm rồi!!!!
\(\left(3x-7\right)^{2015}=\left(3x-7\right)^{2017}\)
\(\Leftrightarrow\left(3x-7\right)^{2017}-\left(3x-7\right)^{2015}=0\)
\(\Leftrightarrow\left(3x-7\right)^2=0\)
\(\Leftrightarrow3x-7=0\)
\(\Leftrightarrow3x=7\Leftrightarrow x=\frac{7}{3}\)
Vậy \(x=\frac{7}{3}\)
\(\left(3x-7\right)^{2015}=\left(3x-7\right)^{2017}\)
\(\Rightarrow\left(3x-7\right)^{2017}-\left(3x-7\right)^{2015}=0\)
\(\Rightarrow\left(3x-7\right)^{2015}\left[\left(3x-7\right)^2-1\right]=0\)
\(\Rightarrow\left(3x-7\right)^{2015}=0\) hoặc \(\left(3x-7\right)^2-1=0\)
+) \(\left(3x-7\right)^{2015}=0\Rightarrow3x-7=0\Rightarrow x=\frac{7}{3}\)
+) \(\left(3x-7\right)^2-1=0\Rightarrow\left(3x-7\right)^2=1\)
\(\Rightarrow\left[\begin{matrix}3x-7=1\\3x-7=-1\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=\frac{8}{3}\\x=2\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{7}{3};\frac{8}{3};2\right\}\)
thiếu 1 trường hợp nữa
(3x-7)2015=(3x-1)2017 =1
Tìm số hữu tỉ x,y biết : (3x-33)^2014+|y-7| ^ 2015<hoặc = 0
Tìm số hữu tỉ x,y biết : (3x-33)^2014 |y-7| ^ 2015<hoặc = 0
Ta có:\(\hept{\begin{cases}\left(3x-33\right)^{2014}\ge0\\\left|y-7\right|^{2015}\ge0\end{cases}}\)\(\Rightarrow\left(3x-33\right)^{2014}+\left|y-7\right|^{2015}\ge0\)
Kết hợp với giả thiết chỉ có \(\left(3x-33\right)^{2014}+\left|y-7\right|^{2015}=0\) đúng
\(\Rightarrow\hept{\begin{cases}3x-33=0\\y-7=0\end{cases}}\)\(\Rightarrow\hept{\begin{cases}x=11\\y=7\end{cases}}\)
Vậy...................
\(\left(3x-33\right)^{2014}-\left(\left|y-7\right|\right)^{2015}\le0\)
Ta có \(\left(3x-33\right)^{2014}\ge0\)với mọi gt \(x\in R\)
và \(\left(\left|y-7\right|\right)^{2015}\ge0\)với mọi gt \(x\in R\)
=> \(\left(3x-33\right)^{2014}-\left(\left|y-7\right|\right)^{2015}\ge0\)với mọi gt \(x\in R\)
Mà \(\left(3x-33\right)^{2014}-\left(\left|y-7\right|\right)^{2015}\le0\)
=> \(\left(3x-33\right)^{2014}-\left(\left|y-7\right|\right)^{2015}=0\)
=> \(\hept{\begin{cases}\left(3x-33\right)^{2014}=0\\\left(\left|y-7\right|\right)^{2015}=0\end{cases}}\)=> \(\hept{\begin{cases}3x-33=0\\y-7=0\end{cases}}\)=> \(\hept{\begin{cases}3x=33\\y=7\end{cases}}\)=> \(\hept{\begin{cases}x=11\\y=7\end{cases}}\)
Tìm số hữu tỉ x,y biết : (3x-33)^2014+|y-7| ^ 2015<hoặc = 0
Ta có:\(\left(3x-33\right)^{2014}\ge0,\left|y-7\right|^{2015}\ge0\Rightarrow\left(3x-33\right)^{2014}+\left|y-7\right|^{2015}\ge0\)
Mà VP\(\le0\)
\(\Rightarrow\left(3x-33\right)^{2014}+\left|y-7\right|^{2015}=0\)
\(\Leftrightarrow\left(3x-33\right)^{2014}=0\Leftrightarrow3x-33=0\Leftrightarrow3x=33\Leftrightarrow x=11\)
\(\Leftrightarrow\left|y-7\right|^{2015}=0\Leftrightarrow\left|y-7\right|=0\Leftrightarrow y-7=0\Leftrightarrow y=7\)
Vậy x=11;y=7
tìm số hữu tỉ x,y biết (3x-33)^2014+/y-7/^2015 <hoặc= 0
tìm x biết 6/(-3).(-5)+6/(-5).(-7)+...+6/(-2015).(-2017)=2014/2017.x