\(\dfrac{x^3-8}{x+7}\left(\dfrac{3}{x-2}-\dfrac{2}{x^2+2x+4}\right)\\ =\dfrac{\left(x-2\right)\left(x^2+2x+4\right)}{x+7}\left(\dfrac{3\left(x^2+2x+4\right)}{\left(x-2\right)\left(x^2+2x+4\right)}-\dfrac{2\left(x-2\right)}{\left(x-2\right)\left(x^2+2x+4\right)}\right)\\ =\dfrac{\left(x-2\right)\left(x^2+2x+4\right)}{x+7}\left(\dfrac{3x^2+6x+12}{\left(x-2\right)\left(x^2+2x+4\right)}-\dfrac{2x-4}{\left(x-2\right)\left(x^2+2x+4\right)}\right)\)

\(=\dfrac{\left(x-2\right)\left(x^2+2x+4\right)}{x+7}.\dfrac{3x^2+6x+12-2x+4}{\left(x-2\right)\left(x^2+2x+4\right)}\)

\(=\dfrac{3x^2+4x+16}{x+7}\)

\(=\dfrac{\left(x-2\right)\left(x^2+2x+4\right)}{x+7}\cdot\dfrac{3x^2+6x+12-2x+4}{\left(x-2\right)\left(x^2+2x+4\right)}\)

\(=\dfrac{3x^2+4x+16}{x+7}\)

-472 + (235 - 28) - (35 - 350)

= -472 + 235 - 28 - 35 + 350

= (-472 - 28) + (235 - 35) + 350

= -500 + 200 + 350

= -500 + 550

= 50

mk chịu !!!!

ai làm đk giúp mik vs ạ

\(\frac{3\left(x-2\right)}{4}\div\frac{2-x}{2}=\frac{3\left(x-2\right)}{4}\times\frac{-2}{x-2}=\frac{-3}{2}\)

học tốt

Rút gọn nhé !

\(\frac{3}{4}.\left(x-2\right):\frac{1}{2}.\left(2-x\right)=\frac{3x-6}{4}.2.\left(2-x\right)\)

\(=\frac{3x-6}{4}.\left(4-2x\right)=\frac{\left(3x-6\right).\left(4-2x\right)}{4}\)

\(=\frac{\left(12x-24\right)-\left(6x^2+12x\right)}{4}=\frac{-24-6x^2}{4}\)

\(=\frac{-12-3x^2}{2}=\frac{-3.\left(4+x^2\right)}{2}\)

\(=\left[\left(-6x\right)+\left(x^2+9\right)\right]\left[\left(-6x\right)-\left(x^2+9\right)\right]\)

\(=\left(-6x\right)^2-\left(x^2+9\right)^2\)

\(=36x^2-\left(x^4+18x^2+81\right)\)

\(=-x^4+18x^2-81\)

\(=-\left(x^4-18x^2+81\right)\)

\(=-\left(x^2-9\right)^2\)

Ta có: \(\left(x^2-6x+9\right)\left(-x^2-6x-9\right)\)

\(=-\left(x^2-6x+9\right)\left(x^2+6x+9\right)\)

\(=-\left[\left(x-3\right)^2\cdot\left(x+3\right)^2\right]\)

\(=-\left(x^2-9\right)^2\)

giúp em  bài với ạ,em cảm ơn, em đang vội ạ

\(a,=-15x^3+10x^4+20x^2\\ b,=2x^3+2x^2+4x-x^2-x-2=2x^3+x^2+3x-2\)