Re
18 x² - 2 x - 9 x + 1 = 0
18 x² - 11 x + 1 = 0
Δ = ( - 11 )² - 4 ( 18 * 1 ) = 121 - 72 = 49
x 1 = ( 11 - 7 ) / 36 = 4/36 = 1 /9
x 2 = ( 11 + 7) / 36 = 18/36 = 1/2
S ( 1/2 : 1 /9 )
