Cho t a n ( x ) = 5 . Tính giá trị của P = 3 s i n ( x ) − 4 c o s ( x ) c o s ( x ) + 2 s i n ( x )

\[{\rm{P = }}\frac{{{\rm{3sin}}\left( {\rm{x}} \right) - {\rm{4cos}}\left( {\rm{x}} \right)}}{{{\rm{cos}}\left( {\rm{x}} \right){\rm{ + 2sin}}\left( {\rm{x}} \right)}}{\rm{ = }}\frac{{\frac{{{\rm{3sin}}\left( {\rm{x}} \right) - {\rm{4cos}}\left( {\rm{x}} \right)}}{{{\rm{cos}}\left( {\rm{x}} \right)}}}}{{\frac{{{\rm{cos}}\left( {\rm{x}} \right){\rm{ + 2sin}}\left( {\rm{x}} \right)}}{{{\rm{cos}}\left( {\rm{x}} \right)}}}}{\rm{ = }}\frac{{{\rm{3tan}}\left( {\rm{x}} \right) - {\rm{4}}}}{{{\rm{1 + 2tan}}\left( {\rm{x}} \right)}}\]

Thay\[{\rm{tan}}\left( {\rm{x}} \right){\rm{ = 5}}\]vào P ta được\[{\rm{P = }}\frac{{{\rm{3}}{\rm{.5}} - {\rm{4}}}}{{{\rm{1 + 2}}{\rm{.5}}}}{\rm{ = 1}}\]

Đáp án cần chọn là: A