Tìm x : 27 . x = - 12;( x - 2 ) . ( x + 7 ) = 0

Tìm x :
a ) 27 . x = - 12
b ) ( x - 2 ) . ( x + 7 ) = 0
c ) ( x- 2 ) . 5 > 0
d ) ( x - 2 ) . ( - 5 ) > 0
e ) ( x + 1 ) . ( - 2 ) < 0