a, \(16x^2-9\left(x+1\right)^2=0\)

\(\Leftrightarrow\left(4x\right)^2-\left(3x+3\right)^2=0\Leftrightarrow\left(4x-3x-3\right)\left(4x+2x+3\right)=0\)

\(\Leftrightarrow\left(x-3\right)\left(6x+3\right)=0\Leftrightarrow x=-\frac{1}{2};x=3\)

b, \(\left(5x-4\right)^2-49x^2=0\Leftrightarrow\left(5x-4-7x\right)\left(5x-4+7x\right)=0\)

\(\Leftrightarrow\left(-2x-4\right)\left(12x-4\right)=0\Leftrightarrow x=-2;x=\frac{1}{3}\)

c, \(5x^3-20x=0\Leftrightarrow5x\left(x^2-4\right)=0\)

\(\Leftrightarrow5x\left(x-2\right)\left(x+2\right)=0\Leftrightarrow x=0;x=\pm2\)

1: Ta có: \(16x^2-9\left(x+1\right)^2=0\)

\(\Leftrightarrow\left(4x-3x-3\right)\left(4x+3x+3\right)=0\)

\(\Leftrightarrow\left(x-3\right)\left(7x+3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{7}{3}\end{matrix}\right.\)

2: Ta có: \(\left(5x-4\right)^2-49x^2=0\)

\(\Leftrightarrow\left(5x-4-7x\right)\left(5x-4+7x\right)=0\)

\(\Leftrightarrow\left(2x+4\right)\left(12x-4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=\dfrac{1}{3}\end{matrix}\right.\)

3: Ta có: \(5x^3-20x=0\)

\(\Leftrightarrow5x\left(x-2\right)\left(x+2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)

Ta có: \(\left(2x+1\right)\left(5x-1\right)=20x^2-16x-1\)

\(\Leftrightarrow10x^2-2x+5x-1-20x^2+16x+1=0\)

\(\Leftrightarrow-10x^2+19x=0\)

\(\Leftrightarrow x\left(-10x+19\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\-10x+19=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\-10x=-19\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\frac{19}{10}\end{matrix}\right.\)

Vậy: \(x\in\left\{0;\frac{19}{10}\right\}\)

D=0 chắc chắn luôn

Thế 2016 cậu để đâu

d: ta có: \(x^2-4x+4=9\left(x-2\right)\)

\(\Leftrightarrow\left(x-2\right)\left(x-11\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=11\end{matrix}\right.\)

a) Thay x = 4 vào biểu thức A :

A = 4⁵ - 5.4⁴+ 5.4³ - 5.4² + 5.4 -1

= 3

b) Thay x = 21 vào B :

B = 21⁶ - 20.21⁵ - 20.21⁴ -20.21³ - 20.21² - 20.21+3

=24

\(4x\left(x^2-5x+3\right)=4x^3-20x^2+12x\)

=> Chọn A