Cho biết \({\left( {3x-1} \right)^2}\; + 2{\left( {x + 3} \right)^2}\; + 11\left( {1 + x} \right)\left( {1-x} \right) = ax + b\) . Khi đó
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A.
\(a = 30; b = 6\) .
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B.
\(a = - 6; b = - 30\) .
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C.
\(a = 6; b = 30\) .
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D.
\(a = - 30; b = - 6\) .
\(\begin{array}{l} {\left( {3x-1} \right)^2}\; + 2{\left( {x + 3} \right)^2}\; + 11\left( {1 + x} \right)\left( {1-x} \right)\\\begin{array}{*{20}{l}}{ = {{\left( {3x} \right)}^2}\;-2.3x.1 + {1^2}\; + 2\left( {{x^2}\; + 6x + 9} \right) + 11\left( {1-{x^2}} \right)}\\{ = 9{x^2}\;-6x + 1 + 2{x^2}\; + 12x + 18 + 11-11{x^2}\;}\\\begin{array}{l} = \left( {9{x^2}\; + 2{x^2}\;-11{x^2}} \right) + \left( { - 6x + 12x} \right){{ + }}\left( {1 + 18 + 11} \right)\\ = 6x + 30\end{array}\end{array}\end{array}\)
\( \Rightarrow a = 6; b = 30\)
Đáp án : C