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: \(5x^3-20x=0\)

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

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

Tích mình đi rồi mình nói thề bạn

x=-5,16769911504425

a) x(x-5)+2(x-5) = (x-5)(x+2)
b) (x-7)(x-2)

c) (x+2)(x^2+2x+4)+5y(x+2) = (x+2)(x^2+2x+4+5y) 

d) (x^2+8)^2 -16x^2 = (x^2+8-4x)(x^2+8+4x)

giải

5x-(4-2x+x^2)(x+2)+x(x-1)(x+1)=0

5x-(4x+8-2x^2-4x+x^3+2x^2)+x(x^2-1)=0

5x-4x-8+2x^2+4x-x^3-2x^2+x^3-1x=0

(5x-4x+4x-1x)+(-8)+(2x^2-2x^2)+(-x^3+x^3)=0

4x+(-8)=0

4x=0+8

4x=8

x=8:4

x=2

D)(4x+1)(16x^2-4x+1)-16x(4x^2-5)=17

64x^3-16x^2+4x+16x^2-4x+1-64x^3+80x=17

80x+1=17

80x=17-1

80x=16

x=1/5

\(5x-\left(4-2x+x^2\right)\left(x+2\right)+x\left(x-1\right)\left(x+1\right)=0\)

\(\Rightarrow5x-\left(4x-2x^2+x^3+8-4x+2x^2\right)+\left(x^2-x\right)\left(x+1\right)=0\)

\(\Rightarrow5x-\left(4x-2x^2+x^3+8-4x+2x^2\right)+\left(x^3+x-x^2-x\right)=0\)

\(\Rightarrow5x-4x+2x^2-x^3-8+4x-2x^2+x^3+x-x^2-x=0\)

\(\Rightarrow4x-8=0\Rightarrow4x=8\Rightarrow x=2\)

Bài 2: Tính giá trị của biểu thức sau:

\(16x^2-y^2=\left(4x+y\right)\left(4x-y\right)\)

Thay \(\hept{\begin{cases}x=87\\y=13\end{cases}}\)

\(\Rightarrow\left(4.87+13\right)\left(4.87-13\right)=361.335=120935\)

Bài 4: Tìm x

a) \(9x^2+x=0\)

\(\Rightarrow x\left(9x+1\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=0\\9x+1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=0\\x=\frac{-1}{9}\end{cases}}\)

b) \(27x^3+x=0\)

\(\Rightarrow x\left(27x^2+1=0\right)\)

\(\Rightarrow\orbr{\begin{cases}x=0\\27x^2+1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=0\\27x^2=\left(-1\right)\end{cases}}\Rightarrow\orbr{\begin{cases}x=0\\x^2=\frac{-1}{27}\end{cases}}\)

Ta có: \(\frac{-1}{27}\) loại vì \(x^2\ge0\forall x\)

Vậy \(x=0\)