Помогите решить!! 1)-12cos36/sin^2 18-cos^2 18 2)38cos153/cos27 3)log_4(3x+7)=2log_4 3

$\frac{12cos 36^{0} }{ sin^{2}18 ^{0} - cos^{2} 18^{0} }= \frac{12cos 36^{0} }{-( cos^{2} 18^{0}- sin^{2} 18 ^{0} )} = \frac{-12cos 36^{0} }{-cos(2* 18^{0} )} = \frac{-12cos 36^{0} }{-cos 36^{0} }=12$
$\frac{38cos 153^{0} }{cos 27^{0} }= \frac{38cos (180^{0}- 27^{0}) }{cos27 ^{0}} = \frac{38*(-cos 27^{0} )}{cos 27^{0} } =-38$
log₄(3x+7)=2*log₄3, log₄(3x+7)=log₄3²
log₄(3x+4)=log₄9
$\left \{ {3x+7\ \textgreater \ 0}} \atop {3x+7=9}} \right., \left \{ {{3x\ \textgreater \ -7} \atop {3x=2}} \right. , \left \{ {{x\ \textgreater \ - \frac{7}{3} } \atop {x= \frac{2}{3} }} \right.$
ответ: x=2/3