= 5a3 - a2b
5 x 27 - 9 x (-4) = 135 + 36 = 171
Смотри.........................
8/19 -17/38 =(8*2 -17)/38 = (16 -17)/38 = -1/38
-1/38 *19/5 = -19/38*5 = -1/2*5 = -1/10 = -0.1
По теореме Виета X1+x2=-b,X1+x2=-5+8, X1+x2 =3, 3=-b, b=-3
x1*x2=-40=c
x^2-3x-40=0