(-2x+1)(-2x-7)=0 помогите

( - 2x + 1)( - 2x - 7) = 04x² + 14x - 2x - 7 = 04x + 12x - 7 = 0D = b² - 4ac = 144 - 4×4×(-7) = 144 + 112 = 256 = 16²x1 = ( - 12 + 16) / 8 = 0,5x2 =( - 12 - 16) / 8 = - 3,5