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Phân tích thành nhân tử
a. \({x^2} + 5x – 6\)
b. \(5{x^2} + 5xy – x – y\)
c. \(7x – 6{x^2} – 2\)
a. \({x^2} + 5x – 6\) \( = {x^2} – x + 6x – 6 = \left( {{x^2} – x} \right) + \left( {6x + 6} \right)\)
\( = x\left( {x – 1} \right) + 6\left( {x – 1} \right) = \left( {x – 1} \right)\left( {x + 6} \right)\)
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b. \(5{x^2} + 5xy – x – y\) \( = \left( {5{x^2} + 5xy} \right) – \left( {x – y} \right) = 5x\left( {x + y} \right) – \left( {x + y} \right)\)
\( = \left( {x + y} \right)\left( {5x – 1} \right)\)
c. \(7x – 6{x^2} – 2\) \( = 4x – 6{x^2} – 2 + 3x = \left( {4x – 6{x^2}} \right) – \left( {2 – 3x} \right)\)
\( = 2x\left( {2 – 3x} \right) – \left( {2 – 3x} \right) = \left( {2 – 3x} \right)\left( {2x – 1} \right)\)