MathematicsMedium175×since 2002Q2721Let f(x)=3sin4x+10sin3x+6sin2x−3f(x) = 3{\sin ^4}x + 10{\sin ^3}x + 6{\sin ^2}x - 3f(x)=3sin4x+10sin3x+6sin2x−3, x∈[−π6,π2]x \in \left[ { - {\pi \over 6},{\pi \over 2}} \right]x∈[−6π,2π]. Then, f is :Aincreasing in (−π6,π2)\left( { - {\pi \over 6},{\pi \over 2}} \right)(−6π,2π)Bdecreasing in (0,π2)\left( {0,{\pi \over 2}} \right)(0,2π)Cincreasing in (−π6,0)\left( { - {\pi \over 6},0} \right)(−6π,0)Ddecreasing in (−π6,0)\left( { - {\pi \over 6},0} \right)(−6π,0)Check answerSkip