Найти Х (7-x) (x+5) - x (4-x) = 14

X * (7X + 35 - X^2 - 5X) - 4X + X^2 = 14

7X^2 + 35X - X^3 - 5X^2 - 4X + X^2 = 14

- X^3 + 3X^2 + 31X - 14 = 0

F ' = - 3X^2 + 6X + 31

...

-3X^2 + 6X + 31 = 0

D = 36 - 4 * (-3) * 31 = 36 - 4 * (-93) = 36+372=408 V D = 20.1

X1 = - 6 + 20.1 / - 6 = - 2.35

X2 = - 6 - 20.1 / - 6 = + 4.35

(7-х) (х+5) - х (4-х) = 14

7 х+35-х (квадрат) + 5 х-4 х+х (квадрат) = 14

7 х+5 х-4 х+35=14

8 х=14-35

8 х=-21

х=-21:8

х=-2.625