B

b

a) \(x\times x+372=472\)

\(x^2=100\)

\(x=10;-10\)

b) \(69,5-x\times x=20,5\)

\(69,5-x^2=20,5\)

\(-x^2+69,5=20,5\)

\(-x^2=-49\)

\(x^2=49\)

\(x=-7;7\)

c) \(x\times x-\dfrac{1}{6}=\dfrac{5}{18}\)

\(x^2=\dfrac{4}{9}\)

\(x=\dfrac{2}{3};-\dfrac{2}{3}\)

Chỗ X.X mình sai phai là X+X mới đúng

2X : X = X

2 = X 

2X + X = 6X 

câu này ko biết chắc sai đề 

2X * X = 10X 

2*X*X=10X

gạch X ở hai vế 

ta có 

2*X=10

X = 10: 2

X= 5

a) Ta có: \(3x-1=0\)

\(\Leftrightarrow3x=1\)

\(\Leftrightarrow x=\dfrac{1}{3}\)

Vậy: \(S=\left\{\dfrac{1}{3}\right\}\)

b) Ta có: \(5x-2=x+4\)

\(\Leftrightarrow5x-x=4+2\)

\(\Leftrightarrow4x=6\)

\(\Leftrightarrow x=\dfrac{3}{2}\)

Vậy: \(S=\left\{\dfrac{3}{2}\right\}\)

\(\left(x-1\right)\left(x.x+1\right)=0\)

\(\Rightarrow\left(x-1\right)\left(x^2+1\right)=0\)

\(\Rightarrow\left[\begin{matrix}x-1=0\\x^2+1=0\end{matrix}\right.\)

\(\Rightarrow\left[\begin{matrix}x=0+1\\x^2=0-1\end{matrix}\right.\)

\(\Rightarrow x=1\)

\(\left(x-1\right)\left(x.x+1\right)=0\\ < =>\left(x-1\right)\left(x^2+1\right)=0\\ =>\left[\begin{matrix}x-1=0\\x^2+1=0\end{matrix}\right.\\ =>\left[\begin{matrix}x=1\left(nhận\right)\\x^2=-1\left(loại\right)\end{matrix}\right.\\ =>x=1\)

\(x.\left(x-\frac{1}{2}\right)=1+x.x\)

\(x^2-\frac{1}{2}x=1+x^2\)

\(\frac{-1}{2}x=1+x^2-x^2\)

\(\frac{-1}{2}x=1\)

\(\Leftrightarrow x=1:\frac{-1}{2}=-2\)

x² - 1/2 x = 1 + x²

-1/2 x = 1

x = -2