( X - 1)*( X - 2 ) = X^2 - 2X - X + 2 = X^2 - 3X + 2
-----------------------------------------------------------
( X - 4)*( X + 3) = X^2 +3X - 4X - 12 = X^2 - X - 12
-------------------------------------------------------
X^2 - 3X + 2 - ( X^2 - X - 12 ) = X^2 - 3X + 2 - X^2 + X + 12 = - 2X + 14
-------------------------------------------------
X = - 0,8
- 2 * ( - 0,8 ) + 14 = 1,6 + 14 = 12,4
--------------------
Ответ 12,4