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Bài 1:
a, 2225 = (23)75 = 875
3150 = (32)75 = 975
Vì 875 < 975 nên 2225 < 3150
b, 212 = (24)3 = 163 ; 418 = (42)9 = 169
Bài 2:
a, 3300 = (33)100 = 27100
5200 = (52)100 = 25100
Vì 27100 > 25100 nên 3300 > 5200
b, Do \(\hept{\begin{cases}\left(x-3\right)^2\ge0\\\left|y^2-25\right|\ge0\end{cases}\forall x,y\Rightarrow\left(x-3\right)^2+\left|y^2-25\right|\ge0}\) (1)
Mà \(\left(x-3\right)^2+\left|y^2-25\right|=0\) (2)
Từ (1) và (2) => \(\hept{\begin{cases}\left(x-3\right)^2=0\\\left|y^2-25\right|=0\end{cases}}\Rightarrow\hept{\begin{cases}x=3\\y=5\end{cases}}\)
Bài 3:
2x = -3y = 4z
=> \(\frac{2x}{12}=\frac{-3y}{12}=\frac{4z}{12}\)
=> \(\frac{x}{6}=\frac{-y}{4}=\frac{z}{3}\)
=> \(\frac{x}{6}=\frac{-2y}{8}=\frac{3z}{9}=\frac{x-2y-3z}{6+8-9}=\frac{30}{5}=6\)
=> x = 36, y = -24, z = 18
a: Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x-1}{2}=\dfrac{y-2}{3}=\dfrac{z-3}{4}=\dfrac{2x+3y-z-2-6+3}{2\cdot2+3\cdot3-4}=5\)
Do đó: x-1=10; y-2=15; z-3=20
=>x=11; y=17; z=23
b: Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{\dfrac{3}{2}}=\dfrac{y}{\dfrac{4}{3}}=\dfrac{z}{\dfrac{5}{4}}=\dfrac{x+y+z}{\dfrac{3}{2}+\dfrac{4}{3}+\dfrac{5}{4}}=\dfrac{49}{\dfrac{49}{12}}=12\)
Do đó: x=18; y=16; z=15
c: \(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{x}{3}=\dfrac{y}{2}\\\dfrac{y}{5}=\dfrac{z}{7}\end{matrix}\right.\Leftrightarrow\dfrac{x}{15}=\dfrac{y}{10}=\dfrac{z}{14}\)
Trường hợp 1: 2x-3y+5z=-1
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{15}=\dfrac{y}{10}=\dfrac{z}{14}=\dfrac{2x-3y+5z}{2\cdot15-3\cdot10+5\cdot14}=\dfrac{-1}{70}\)
Do đó: x=-15/70=-3/14; y=-10/70=-1/7; z=-14/70=-1/5
Trường hợp 2: 2x-3y+5z=1
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{15}=\dfrac{y}{10}=\dfrac{z}{14}=\dfrac{2x-3y+5z}{2\cdot15-3\cdot10+5\cdot14}=\dfrac{1}{70}\)
Do đó: x=15/70=3/14; y=1/7; z=1/5
Bài 1:
a: A=2x+5-|x-3|
=2x+5-(x-3)
=2x+5-x+3
=x+8
b: \(B=\left|2x-4\right|+3x-7\)
mà x<2
nên B=4-2x+3x-7=x-3
c: \(C=5x-3-2\left|x-1\right|\)
Trường hợp 1: x>=1
C=5x-3-2(x-1)=5x-3-2x+2=3x-1
Trường hợp 2: x<1
C=5x-3-2(1-x)=5x-3-2+2x=7x-5
\(\left|x-\frac{1}{3}\right|+\frac{4}{5}=\left|\left(-3,2\right)+\frac{2}{5}\right|\)
\(\left|x-\frac{1}{3}\right|+\frac{4}{5}=\frac{14}{5}\)
\(\left|x-\frac{1}{3}\right|=2\)
=> \(x-\frac{1}{3}=2\) hoặc \(x-\frac{1}{3}=-2\)
x = \(\frac{7}{3}\) x = \(\frac{-5}{3}\)
Vậy x = \(\frac{7}{3}\)hoặc x = \(\frac{-5}{3}\)
a)(x − 12)2 = 0
=>x − 12 = 0
=> x = 12
b) (x+12)2 = 0,25
=> x + 12 = 0,5 hoặc x + 12= -0,5
=> x = -11,5 hoặc x = -12,5
c) (2x−3)3 = -8
=> 2x - 3 = -2
=> x = 0,5
d) (3x−2)5 = −243
=> 3x - 2 = -3
=> x = -1/3
e) (7x+2)-1 = 3-2
=> \(\dfrac{1}{7x+2}=\dfrac{1}{9}\)
=> 7x + 2 = 9
=> x = 1
f) (x−1)3 = −125
=> (x−1) = −5
=> x = -4
g) (2x−1)4 = 81
=> 2x - 1 = 3
=> x = 2
h) (2x−1)6 = (2x−1)8
=> 2x -1 = 0 hoặc 2x - 1 = 1 hoặc 2x - 1 = -1
=> x = 1/2 hoặc x = 1 hoặc x = 0
a/ \(\left(x-\dfrac{1}{2}\right)^2=0\)
\(\Leftrightarrow x-\dfrac{1}{2}=0\)
\(\Leftrightarrow x=\dfrac{1}{2}\)
Vậy ...
b/ \(\left(x+\dfrac{1}{2}\right)^2=\dfrac{1}{4}\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(x+\dfrac{1}{2}\right)^2=\left(\dfrac{1}{2}\right)^2\\\left(x+\dfrac{1}{2}\right)^2=\left(-\dfrac{1}{2}\right)^2\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=\dfrac{1}{2}\\x+\dfrac{1}{2}=-\dfrac{1}{2}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)
Vậy ..
c/ \(\left(2x-3\right)^3=-8\)
\(\Leftrightarrow\left(2x-3\right)^3=\left(-2\right)^3\)
\(\Leftrightarrow2x-3=-2\)
\(\Leftrightarrow x=\dfrac{1}{2}\)
Vậy ...
d/ \(\left(3x-2\right)^5=-243\)
\(\left(3x-2\right)^5=\left(-3\right)^5\)
\(\Leftrightarrow3x-2=-3\)
\(\Leftrightarrow x=-\dfrac{1}{3}\)
Vậy ...
e/ \(\left(x-1\right)^3=-125\)
\(\Leftrightarrow\left(x-1\right)^3=\left(-5\right)^3\)
\(\Leftrightarrow x-1=-5\)
\(\Leftrightarrow x=-4\)
Vậy..
f/ \(\left(2x-1\right)^4=81\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(2x-1\right)^4=3^4\\\left(2x-1\right)^4=\left(-3\right)^4\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-1=3\\2x-1=-3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\)
Vậy...
g/ \(\left(2x-1\right)^6=\left(2x-1\right)^8\)
\(\Leftrightarrow\left(2x-1\right)^8-\left(2x-1\right)^6=0\)
\(\Leftrightarrow\left(2x-1\right)^6\left[\left(2x-1\right)^2-1\right]=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(2x-1\right)^6=0\\\left(2x-1\right)^2-1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-1=0\\\left[{}\begin{matrix}2x-1=1\\2x-1=-1\end{matrix}\right.\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\\left[{}\begin{matrix}x=1\\x=0\end{matrix}\right.\end{matrix}\right.\)
Vậy..
a) \(\left|2-x\right|+x=-3\\ \Rightarrow\left|2-x\right|=-3-x\left(ĐK:-3-x\ge0\right)\\ \Rightarrow\left[{}\begin{matrix}2-x=-3-x\\2-x=3+x\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x-x=-3-2\\-x-x=3-2\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}0=-5\left(\text{vô lí}\right)\\-2x=1\end{matrix}\right.\Rightarrow x=\frac{-1}{2}\left(ktm\text{ }-3-x\ge0\right)\)
Vậy \(x\in\varnothing\)
b) \(\left|x-1\right|+1=2x-3\\ \Rightarrow\left|x-1\right|=2x-4\left(ĐK:2x-4\ge0\right)\\ \Rightarrow\left[{}\begin{matrix}x-1=2x-4\\x-1=-2x+4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x-x=4-1\\x+2x=1+4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=3\left(t/m\right)\\3x=5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\left(t/m\right)\\x=\frac{5}{3}\left(ktm\right)\end{matrix}\right.\)
Vậy x = 3
c) \(\left|\frac{4}{3}x-\frac{4}{3}+\frac{1}{2}\right|=\left|2x-2+\frac{1}{3}\right|\\ \Rightarrow\left[{}\begin{matrix}\frac{4}{3}x-\frac{4}{3}+\frac{1}{2}=2x-2+\frac{1}{3}\\\frac{4}{3}x-\frac{4}{3}+\frac{1}{2}=-2x+2-\frac{1}{3}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x-\frac{4}{3}x=2-\frac{1}{3}-\frac{4}{3}+\frac{1}{2}\\\frac{4}{3}x+2x=\frac{4}{3}-\frac{1}{2}+2-\frac{1}{3}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}\frac{2}{3}x=\frac{5}{6}\\\frac{10}{3}x=\frac{5}{2}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{5}{4}\\x=\frac{3}{4}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{5}{4};\frac{3}{4}\right\}\)