Tìm x, biết: a) 2(x^2 + 3) - 2x(3 + x) = 0; b) (12x - 5)(4x - 1) + (3x - 7)(1 - 16x) = 81

Bài 1 :
a. x( 8x -2 ) - 8x^2 + 12x
b. 6x^ 2- 2x ( 3x - 5 )
c. 2 ( x^2 +x) - 2x ( 3+x )
d. 5 (2x -1 ) - 4 ( 8-3x )
Bài 2 : Tìm x
a. 2 ( x^2 +3 ) - 2x ( 3 +x ) = 0
b. ( 12x -5 ) ( 4x - 1 ) +( 3x - 7 )( 1 -16x ) =81
c. ( x + 2 ) ( x^2 - 2x +4 ) - x ( x^2 - 2 ) = 15