rút gọn phân thức
x mũ 2 + 4x + 3 / 2x + 6
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\(\frac{x^6+2x^3y^3+y^6}{x^7-xy^6}\)( ĐKXĐ tự tìm nhé *)
\(=\frac{\left(x^3\right)^2+2x^3y^3+\left(y^3\right)^2}{x\left(x^6-y^6\right)}\)
\(=\frac{\left(x^3+y^3\right)^2}{x\left[\left(x^3\right)^2-\left(y^3\right)^2\right]}\)
\(=\frac{\left[\left(x+y\right)\left(x^2-xy+y^2\right)\right]^2}{x\left(x^3-y^3\right)\left(x^3+y^3\right)}\)
\(=\frac{\left[\left(x+y\right)\left(x^2-xy+y^2\right)\right]^2}{x\left(x-y\right)\left(x^2+xy+y^2\right)\left(x+y\right)\left(x^2-xy+y^2\right)}\)
\(=\frac{\left(x+y\right)\left(x^2-xy+y^2\right)}{x\left(x-y\right)\left(x^2+xy+y^2\right)}\)
\(=\frac{x^3+y^3}{x\left(x^3-y^3\right)}=\frac{x^3+y^3}{x^4-xy^3}\)
`@` `\text {Ans}`
`\downarrow`
\(3(x^2+2x-3)+3(-x^2-4x)\)
`= 3*(x^2+2x-3 - x^2 - 4x)`
`= 3*[(x^2-x^2)+(2x-4x)-3]`
`= 3*(-2x-3)`
`= -6x-9`
3(x² + 2x - 3) + 3(-x² - 4x)
= 3x² + 6x - 9 - 3x² - 12x
= (3x² - 3x²) + (6x - 12x) - 9
= -6x - 9
\(a,=\dfrac{\left(x+1\right)^2}{x\left(x+1\right)}=\dfrac{x+1}{x}\\ b,=\dfrac{-\left(x^2-5x-6\right)}{\left(x+2\right)^2}=\dfrac{-\left(x+1\right)\left(x-6\right)}{\left(x+2\right)^2}\)
\(\frac{x^2+4x+3}{2x+6}\)
\(=\frac{x^2+3x+x+3}{2\left(x+3\right)}\)
\(=\frac{x\left(x+3\right)+\left(x+3\right)}{2\left(x+3\right)}\)
\(=\frac{\left(x+1\right)\left(x+3\right)}{2\left(x+3\right)}\)
\(=\frac{x+1}{2}\)
\(\frac{x^2+4x+3}{2x+6}\)
ĐKXĐ : x ≠ -3
\(=\frac{x^2+3x+x+3}{2\left(x+3\right)}\)
\(=\frac{x\left(x+3\right)+\left(x+3\right)}{2\left(x+3\right)}\)
\(=\frac{\left(x+3\right)\left(x+1\right)}{2\left(x+3\right)}\)
\(=\frac{x+1}{2}\)