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Rút gọn các biểu thức sau
a. \(x\left( {2{x^2} – 3} \right) – {x^2}\left( {5x + 1} \right) + {x^2}\)
b. \(3x\left( {x – 2} \right) – 5x\left( {1 – x} \right) – 8\left( {{x^2} – 3} \right)\)
c. \({1 \over 2}{x^2}\left( {6x – 3} \right) – x\left( {{x^2} + {1 \over 2}} \right) + {1 \over 2}\left( {x + 4} \right)\)
a. \(x\left( {2{x^2} – 3} \right) – {x^2}\left( {5x + 1} \right) + {x^2}\)=\(2{x^3} – 3x – 5{x^3} – {x^2} + {x^2} = – 3x – 3{x^3}\)
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b. \(3x\left( {x – 2} \right) – 5x\left( {1 – x} \right) – 8\left( {{x^2} – 3} \right)\)
\( = 3{x^2} – 6x – 5x + 5{x^2} – 8{x^2} + 24 = – 11x + 24\)
c. \({1 \over 2}{x^2}\left( {6x – 3} \right) – x\left( {{x^2} + {1 \over 2}} \right) + {1 \over 2}\left( {x + 4} \right)\)
\( = 3{x^3} – {3 \over 2}x – {x^3} – {1 \over 2}x + {1 \over 2}x + 2 = 2{x^3} – {3 \over 2}x + 2\)