Tìm x biết \(\left(x+2\right)^{n+1}=\left(x+2\right)^{n+11}\)
Tìm x biết:\(\left(x+2\right)^{n+1}\)=\(\left(x+2\right)^{n+11}\) với n là số tự nhiên
(\(x\) + 2)n+1 = ( \(x\) + 2)n+11
(\(x+2\))n+1 - ( \(x\) + 2)n+11 = 0
(\(x\) + 2)n+1.( 1 + (\(x\) + 2)10) = 0
(\(x\) + 2)10 + 1 > 0 ∀ \(x\)
=> (\(x\) + 2)n+1 = 0 ⇒ \(x\) + 2 = 0 ⇒ \(x\) = -2
vậy \(x\) = -2
a) Tìm số tự nhiên n biết \(\left(n-1\right)^{n+11}-\left(n-1\right)^n=0\)
b) Tìm x biết: \(3\left(x-2\right)-4\left(2x+1\right)-5\left(2x+3\right)=50\)
c) Tìm x biết: \(\left|2x-3\right|=\left|2-x\right|\)
b) 3x - 6 - (8x + 4) - (10x + 15) = 50
=> 3x - 6 - 8x - 4 - 10x - 15 = 50
=> (3x - 8x - 10x) = 6+ 4 + 15 + 50
=> -15x = 75 => x = 75 : (-15) = -5
c) => 2x - 3 = 2 - x hoặc 2x - 3 = - (2 - x) (Vì 2 số có giá trị tuyệt đối bằng nhau thì chings bằng nhau hoặc đối nhau)
+) nếu 2x - 3 = 2 - x => 2x+ x = 2 + 3 => 3x = 5 => x = 5/3
+) nếu 2x - 3 = -(2 - x) => 2x - 3 = -2 + x => 2x - x = -2 + 3 => x = 1
Vậy x = 5/3 hoặc x = 1
a) (n-1)n+11-(n-1)n=0
(n-1)n(n-1)11-(n-1)n=0
(n-1)n[(n-1)11-1]=0
(n-1)n=0 hoặc (n-1)11-1=0
n-1=0 hoặc (n-1)11 =1
n=1 hoặc n-1 =1
n=1 hoặc n =2
Cho hàm số y= h(x) = (\(\left(n^2-2\right)x+2\left(n^2-1\right)-3\)Tìm n biết h(3)- 2h(1)= 11
tìm x
\(\left(x+2\right)^{n+1}=\left(x+2\right)^{n+11}\)
\(\left(x+2\right)^{n+1}=\left(x+2\right)^{n+11}\)
\(\Leftrightarrow\orbr{\begin{cases}x+2=1\\x+2=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-1\\x=-2\end{cases}}}\)
\(\left(x+2\right)^{n+1}-\left(x+2\right)^{x+11}=0\\ \Leftrightarrow\left(x+2\right)^{n+1}\left(1-\left(x+2\right)^{10}\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}\left(x+2\right)^{n+1}=0\\1-\left(x+2\right)^{10}=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-2\\\left(x+2\right)^{10}=1\Rightarrow x+2=-1\Rightarrow x=-3\end{cases}}}\)
\(\Rightarrow\left(x+2\right)^{n+11}-\left(x+2\right)^{n+1}=0\)
\(\Rightarrow\left(x+2\right)^n.\left(x+2\right)^{11}-\left(x+2\right)^n.\left(x+2\right)=0\)
\(\Rightarrow\left[\left(x+2\right)^n.\left(x+2\right)\right].\left[\left(x+2\right)^{10}-1\right]=0\)
\(\Rightarrow\orbr{\begin{cases}\left(x+2\right)^n.\left(x+2\right)=0\\\left(x+2\right)^{10}-1=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x+2=0\\\orbr{\begin{cases}x+2=1\\x+2=-1\end{cases}}\end{cases}}\)
đến đây bạn tự làm típ nha thanks
Bài 3: Tìm x biết:
1, \(4x^2-36=0\)
2, \(\left(x-1\right)^2+x\left(4-x\right)=11\)
3, \(\left(x-5\right)^2-x.\left(x+2\right)=5\)
4, \(x\left(x+4\right)-x^2-6x=10\)
1: Ta có: \(4x^2-36=0\)
\(\Leftrightarrow\left(x-3\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)
2: Ta có: \(\left(x-1\right)^2+x\left(4-x\right)=11\)
\(\Leftrightarrow x^2-2x+1+4x-x^2=11\)
\(\Leftrightarrow2x=10\)
hay x=5
\(\text{Tìm x, biết:}\)
\(a\)) \(\left(19x+2.5^2\right):14=\left(13-8\right)^2-4^2\)
\(b\)) \(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+30\right)=1240\)
\(c\)) \(11-\left(-53+x\right)=97\)
\(d\)) \(-\left(x+84\right)+213=-16\)
BT9: Tìm x biết
\(9,\left(2x-5\right)^2-\left(x+1\right)^2=0\)
\(10,\left(x+3\right)^2-x^2=45\)
\(11,\left(5x-4\right)^2-49x^2=0\)
\(12,16\left(x-1\right)^2-25=0\)
\(9,\left(2x-5\right)^2-\left(x+1\right)^2=0\\ \Leftrightarrow\left(2x-5-x-1\right)\left(2x-5+x+1\right)=0\)
\(\Leftrightarrow\left(x-6\right)\left(3x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-6=0\\3x-4=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=\dfrac{4}{3}\end{matrix}\right.\)
Vậy \(S=\left\{6;\dfrac{4}{3}\right\}\)
\(10,\left(x+3\right)^2-x^2=45\)
\(\Leftrightarrow x^2+6x+9-x^2-45=0\\ \Leftrightarrow6x=36\\ \Leftrightarrow x=6\)
Vậy \(S=\left\{6\right\}\)
\(11,\left(5x-4\right)^2-49x^2=0\\ \Leftrightarrow\left(5x-4\right)^2-\left(7x\right)^2=0\\ \Leftrightarrow\left(5x-4-7x\right)\left(5x-4+7x\right)=0\\ \Leftrightarrow\left(-2x-4\right)\left(12x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}-2x-4=0\\12x-4=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=\dfrac{1}{3}\end{matrix}\right.\)
Vậy \(S=\left\{-2;\dfrac{1}{3}\right\}\)
\(12,16\left(x-1\right)^2-25=0\\ \Leftrightarrow4^2\left(x-1\right)^2-5^2=0\\ \Leftrightarrow\left[4\left(x-1\right)\right]^2-5^2=0\\ \Leftrightarrow\left(4x-4\right)^2-5^2=0\\ \Leftrightarrow\left(4x-4-5\right)\left(4x-4+5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}4x-9=0\\4x+1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{9}{4}\\x=-\dfrac{1}{4}\end{matrix}\right.\)
Vậy \(S=\left\{-\dfrac{1}{4};\dfrac{9}{4}\right\}\)
so sánh: \(A=26^2-24^2\) và \(B=27^2-25^2\)
tìm x, biết:
\(4\left(x+1\right)^2+\left(2x-1\right)^2-8\left(x-1\right)\left(x+1\right)=11\)
Bài 1:
\(A=26^2-24^2=\left(26-24\right)\left(26+24\right)=2\cdot50=100\)
\(B=27^2-25^2=\left(27-25\right)\left(27+25\right)=2\cdot52=104\)
=>A<B
Bài 2:
\(4\left(x+1\right)^2+\left(2x-1\right)^2-8\left(x-1\right)\left(x+1\right)=11\)
=>\(4\left(x^2+2x+1\right)+4x^2-4x+1-8\left(x^2-1\right)=11\)
=>\(4x^2+8x+4+4x^2-4x+1-8x^2+8=11\)
=>4x+13=11
=>4x=-2
=>\(x=-\dfrac{1}{2}\)
\(\left(x+2\right)^{n+1}=\left(x+2\right)^{n+11}\left\{n\in N\right\}\)
\(\left(x+2\right)^{n+1}=\left(x+2\right)^{n+11}\)
\(\Leftrightarrow\left(x+2\right)^{n+1}-\left(x+2\right)^{n+11}=0\)
\(\Leftrightarrow\left(x+2\right)^{n+1}-\left(x+2\right)^{n+1}\cdot\left(x+2\right)^{10}=0\)
\(\Leftrightarrow\left(x+2\right)^{n+1}\left[1-\left(x+2\right)^{10}\right]=0\)
\(\Leftrightarrow\orbr{\begin{cases}\left(x+2\right)^{n+1}=0\\1-\left(x+2\right)^{10}=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x+2=0\\x+2\in\left\{\pm1\right\}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=-2\\x\in\left\{-1;-3\right\}\end{cases}}\)
Vậy....
=> (x+2)n+11:(x+2)n+1=1
<=> (x+2)10=1
th1:x+2=1
<=>x=-1
th2:x+2=-1
<=>x=-3
vậy x=-1 hoặc x=-3