Ta có \(\frac{32x-8x^2+2x^3}{x^3+64}=\frac{x\left(32-8x+2x^2\right)}{\left(x+4\right)\left(x^2-4x+16\right)}=\frac{2x\left(x^2-4x+16\right)}{\left(x+4\right)\left(x^2-4x+16\right)}=\frac{2x}{x+4}\)

khó qua mik mới hc lớp 7 thôi

Nguyễn Huệ Lam ơi cái câu b bn làm sai r cái đoạn đặt ntu chung là 2 x đầu tiên ấy bn

a)

\(\frac{9-\left(x+5\right)^2}{x^2+4x+4}=\frac{3^2-\left(x+5\right)^2}{x^2+2.x.2+2^2}=\frac{\left(3+x+5\right)\left(3-x-5\right)}{\left(x+2\right)^2}\)

\(=\frac{\left(x+8\right)\left(x-2\right)}{\left(x+2\right)^2}\)

b)

\(\frac{32x-8x^2+2x^3}{x^3+64}=\frac{2x\left(x^2-8x+16\right)}{x^3+4^3}=\frac{2x\left(x^2-2.x.4+4^2\right)}{\left(x+4\right)\left(x^2-4x+16\right)}\)

\(=\frac{2x\left(x-4\right)^2}{\left(x+4\right)\left(x^2-4x+16\right)}\)

a) (2x^2 +2xy - xy -y^2 ) / (2x^2 - 2xy - xy +y^2)

= 2x(x+y) - y(x+y)  /  2x(x-y) - y(x-y)

= (2x-y)(x+y)  /  (2x-y)(x-y)

= x+y/x-y

Rút gọn cái sau:

\(\frac{32x+4x^2+2x^3}{x^3+64}\)

\(=\frac{2x\left(x^2+2x+16\right)}{\left(x+4\right)\left(x^2-4x+16\right)}\)

Đề có vẻ sai sai ? 

\(A =\frac{32x - 8x^{2} + 2x^{3}}{x^{3}+ 64}\)\(= \frac{2x(16 - 4x + x^{2})}{(x + 4)(x^{2} - 4x + 16)}= \frac{2x(x^{2} - 4x + 16)}{(x + 4)(x^{2} - 4x + 16)}= \frac{2x}{x + 4}\)

\(A=\dfrac{32x-8x^2+2x^3}{x^3+64}\)

\(=\dfrac{2x\left(16-4x+x^2\right)}{\left(x+4\right)\left(x^2-4x+16\right)}\)

\(=\dfrac{2x\left(x^2-4x+16\right)}{\left(x+4\right)\left(x^2-4x+16\right)}\)

\(=\dfrac{2x}{x+4}\).

Câu 5: B

Câu 6: 

a: ĐKXĐ: \(x-2\ne0\)

=>\(x\ne2\)

b: ĐKXĐ: \(x+1\ne0\)

=>\(x\ne-1\)

8:

\(A=\dfrac{x^2+4}{3x^2-6x}+\dfrac{5x+2}{3x}-\dfrac{4x}{3x^2-6x}\)

\(=\dfrac{x^2+4-4x}{3x\left(x-2\right)}+\dfrac{5x+2}{3x}\)

\(=\dfrac{\left(x-2\right)^2}{3x\left(x-2\right)}+\dfrac{5x+2}{3x}\)

\(=\dfrac{x-2+5x+2}{3x}=\dfrac{6x}{3x}=2\)

7: 

\(\dfrac{8x^3yz}{24xy^2}\)

\(=\dfrac{8xy\cdot x^2z}{8xy\cdot3y}\)

\(=\dfrac{x^2z}{3y}\)