Toán Lớp 8: a) 2 / x(x-3)^2 ; 5 / 2x(x-3) mẫu thức chung của hai phân thức này là gì?
b) rút gọn x(x-2)^2+4x+8 / (x^3-8)
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Toán Lớp 8: a) 2 / x(x-3)^2 ; 5 / 2x(x-3) mẫu thức chung của hai phân thức này là gì?
b) rút gọn x(x-2)^2+4x+8 / (x^3-8)
Comments ( 1 )
a)\dfrac{4}{{2x{{\left( {x – 3} \right)}^2}}}\\
\dfrac{{5x – 15}}{{2x{{\left( {x – 3} \right)}^2}}}\\
b)\dfrac{{{x^3} – 4{x^2} + 8x + 8}}{{{x^3} – 8}}
\end{array}\)
a)\dfrac{2}{{x{{\left( {x – 3} \right)}^2}}} = \dfrac{{2.2}}{{2x{{\left( {x – 3} \right)}^2}}} = \dfrac{4}{{2x{{\left( {x – 3} \right)}^2}}}\\
\dfrac{5}{{2x\left( {x – 3} \right)}} = \dfrac{{5\left( {x – 3} \right)}}{{2x{{\left( {x – 3} \right)}^2}}} = \dfrac{{5x – 15}}{{2x{{\left( {x – 3} \right)}^2}}}\\
b)\dfrac{{x{{\left( {x – 2} \right)}^2} + 4x + 8}}{{{x^3} – 8}}\\
= \dfrac{{x\left( {{x^2} – 4x + 4} \right) + 4x + 8}}{{{x^3} – 8}}\\
= \dfrac{{{x^3} – 4{x^2} + 4x + 4x + 8}}{{{x^3} – 8}}\\
= \dfrac{{{x^3} – 4{x^2} + 8x + 8}}{{{x^3} – 8}}
\end{array}\)