Tìm x, biết:
X+298:10-93.10-205=0
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\(x^2+2x-10=0\)
\(\Leftrightarrow x^2+2x+1-9=0\)
\(\Leftrightarrow\left(x+1\right)^2-9=0\\\)
\(\Leftrightarrow\left(x+1\right)^2=9\)
\(\Leftrightarrow\left(x+1\right)^2=\pm\sqrt{9}\)
\(\Leftrightarrow\left(x+1\right)^2=\left(\pm3\right)^2\)
\(\Leftrightarrow\left[{}\begin{matrix}x+1=3\\x+1=-3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3-1\\x=-3-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-4\end{matrix}\right.\)
Vậy S={2;-4}
\(x^3-x=0\Rightarrow x\left(x^2-1\right)=0\)
TH1: \(x=0\)
TH2: \(x^2-1=0\Rightarrow x^2=1\Rightarrow x=\sqrt{1}\)hoặc \(x=-\sqrt{1}\)
x + 1 : 0,75 = 1,4 : 0,25
<=> \(x+\dfrac{4}{3}=5,6\)
<=> \(x=\dfrac{64}{15}\)
\(\frac{x+2}{x-5}< 0\) <=> x+2 và x-5 trái dấu
Mà x+2 > x-5
Nên x+2 > 0 và x-5 < 0
=>x > -2 và x < 5
Vậy -2 <x <5
Lời giải:
$\frac{x+7}{x}=9$
$x+7=9\times x$
$7=9\times x-x$
$7=8\times x$
$x=7:8=\frac{7}{8}$
x.(x-5)+x-5=o
=> x.(x-5)+(x-5)=0
=>(x-5)(x+1)=0
=> x-5=0 =>x=5
x+1=0 x=-1
\(...\Rightarrow x+x+\dfrac{x}{43}+\dfrac{x}{8}=14+148+\dfrac{10}{30}+\dfrac{5}{95}\)
\(\Rightarrow\left(1+1+\dfrac{1}{43}+\dfrac{1}{8}\right)x=162+\dfrac{1}{3}+\dfrac{1}{19}\)
\(\Rightarrow\left(\dfrac{2.43.8}{43.8}+\dfrac{1.8}{43.8}+\dfrac{1.43}{43.8}\right)x=\dfrac{162.3.19}{3.19}+\dfrac{1.19}{3.19}+\dfrac{1.3}{19.3}\)
\(\Rightarrow\left(\dfrac{688}{344}+\dfrac{8}{344}+\dfrac{43}{344}\right)x=\dfrac{9234}{57}+\dfrac{19}{57}+\dfrac{3}{57}\)
\(\Rightarrow\dfrac{739}{344}x=\dfrac{9256}{57}\)
\(\Rightarrow x=\dfrac{9256}{57}:\dfrac{739}{344}=\dfrac{9256}{57}.\dfrac{344}{739}=\dfrac{\text{3184064}}{\text{42123}}\)
=> x+29,8-930-205=0
=> x=0+205+930-29,8
=> x=1105,2