tìm x,biết
\(\left|2x-5\right|=3\)
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Tìm x biết:
\(\left(2x-3\right)^3\)=\(\left(2x-3\right)^5\)
\((2x-3)^3=(2x-3)^5\\\Rightarrow (2x-3)^3-(2x-3)^5=0\\\Rightarrow (2x-3)^3[1-(2x-3)^2]=0\)
\(\Rightarrow\left[{}\begin{matrix}\left(2x-3\right)^3=0\\1-\left(2x-3\right)^2=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}2x-3=0\\\left(2x-3\right)^2=1\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}2x=3\\2x-3=1\\2x-3=-1\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\2x=4\\2x=2\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=2\\x=1\end{matrix}\right.\)
\(Vậy:x\in\left\{1;\dfrac{3}{2};2\right\}\)
Tìm x biết \(\left|5\left(2x+3\right)\right|+\left|2\left(2x+3\right)\right|+\left|2x+3\right|=16\)
NX: 2x+3; 5(2x+3) và 2(2x+3) cùng dấu
+TH1: 2x+3 \(\ge\)0 => x \(\ge\frac{-3}{2}\)
=> 5(2x+3), 2(2x+3) \(\ge\)0
=> |5(2x+3)| = 5(2x+3); |2(2x+3)| = 2(2x+3); |2x+3| = 2x+3
=> (2x+3)(5+2+1) = 16
=> 2x+3 = 2
=> 2x = -1
=> x = -1/2 (t/m)
+ TH2: 2x+3 < 0 => x < -3/2
cmtt => -5(2x+3) - 2(2x+3) - (2x+3) = 16
=> (2x+3)(-5-2-1) = 16
=> 2x+3 = -2
=> 2x = -5
=> x = -5/2 (t/m)
/8(2x+3/ = 16
/2x+3/=2
2x+3=2 hoặc 2x+3=-2
2x=-1 hoặc 2x=-5
x=-1/2 hoặc x=-5/2
bạn trả lời nhé
Tìm \(x\) biết:
\(\left(2x-1\right)^3\)\(-2x\left(4x^2-3x\right)=5\)
\(\Leftrightarrow\left(8x^3-12x^2+6x-1\right)-\left(8x^3-6x^2\right)=5\)
\(\Leftrightarrow8x^3-12x^2+6x-1-8x^3+6x^2=5\)
\(\Leftrightarrow6x^2-6x+6=0\)
\(\Leftrightarrow x^2-x+1=0\)
\(\Leftrightarrow\left(x-\dfrac{1}{2}\right)^2+\dfrac{3}{4}=0\)
Do \(\left(x-\dfrac{1}{2}\right)^2\ge0;\forall x\Rightarrow\left(x-\dfrac{1}{2}\right)^2+\dfrac{3}{4}>0;\forall x\)
\(\Rightarrow\) Phương trình vô nghiệm
Ta có: \(\left(2x-1\right)^3-2x\left(4x^2-3x\right)=5\)
\(\Leftrightarrow8x^3-6x^2+12x-1-8x^3+6x^2=5\)
\(\Leftrightarrow12x=6\)
hay \(x=\dfrac{1}{2}\)
Tìm x biết :
\(\left|x-3\right|-2\left|5-2x\right|=11\)
Tìm \(x\) biết:
\(\left(\sqrt{3}\right)^x=243\)
\(0,1^x=1000\)
\(\left(\dfrac{1}{2}\right)^x=1024\)
\(\left(0,2\right)^{x+3}< \dfrac{1}{5}\)
\(\left(\dfrac{3}{5}\right)^{2x+1}>\left(\dfrac{5}{3}\right)^2\)
\(5^{x-1}+5^{x+2}=3\)
a: \(\left(\sqrt{3}\right)^x=243\)
=>\(3^{\dfrac{1}{2}\cdot x}=3^5\)
=>\(\dfrac{1}{2}\cdot x=5\)
=>x=10
b: \(0,1^x=1000\)
=>\(\left(\dfrac{1}{10}\right)^x=1000\)
=>\(10^{-x}=10^3\)
=>-x=3
=>x=-3
c: \(\left(0,2\right)^{x+3}< \dfrac{1}{5}\)
=>\(\left(0,2\right)^{x+3}< 0,2\)
=>x+3>1
=>x>-2
d: \(\left(\dfrac{3}{5}\right)^{2x+1}>\left(\dfrac{5}{3}\right)^2\)
=>\(\left(\dfrac{3}{5}\right)^{2x+1}>\left(\dfrac{3}{5}\right)^{-2}\)
=>2x+1<-2
=>2x<-3
=>\(x< -\dfrac{3}{2}\)
e: \(5^{x-1}+5^{x+2}=3\)
=>\(5^x\cdot\dfrac{1}{5}+5^x\cdot25=3\)
=>\(5^x=\dfrac{3}{25,2}=\dfrac{1}{8,4}=\dfrac{10}{84}=\dfrac{5}{42}\)
=>\(x=log_5\left(\dfrac{5}{42}\right)=1-log_542\)
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
Tìm x,biết :
\(x.\left(x-5\right).\left(x+5\right)-\left(x+2\right).\left(x^2-2x+4\right)=3\)
\(x\left(x^2-5^2\right)-\left(x^3+2^3\right)=3\)
\(x^3-25x-x^3-8=3\)
\(-25x-8=3\)
\(-25x=3+8=11\)
\(x=\frac{-11}{25}\)
Tìm x, biết:
\(2x\left(x-5\right)-x\left(3+2x\right)=26\)
\(2x^2-10x-3x-2x^2=26\)
\(2x^2-13x-2x^2=26\)
\(-13x=26\)
\(x=-2\)
\(2x\left(x-5\right)-x\left(3+2x\right)=26\)
\(\Leftrightarrow\left(2x^2-10x\right)-\left(3x+2x^2\right)=26\)
\(\Leftrightarrow-13x=26\)
\(\Leftrightarrow x=-2\)
Tìm X, biết
\(3\left(x-2\right)-4\left(2x+1\right)-5\left(2x+3\right)=50\)
3(x-2)-4(2x+1)-5(2x+3)=50
3x-6-8x-4-10x-13=50
-15x-23=50
-15x=50+23
-15x=73
x=73:(-15)
x=\(-\frac{73}{15}\)
xin lỗi em, chị nhầm, để chị làm lại nha:
3(x-2)-4(2x+1)-5(2x+3)=50
3x-6-8x-4-10x-15=50
-15x-25=50
-15x=50+25
-15x=75
x=75:(-15)
x=-5
em xem lần chị làm lại này nha. chúc em học tốt
Tìm số tự nhiên x , biết
\(2\cdot\left(x-1\right)^2=8\)
\(\left(2x+1\right)^3=125\)
\(\left(x-2\right)^5=243\)
\(5\left(x-4\right)^2-7=13\)
\(221-\left(3x+2\right)^3=96\)