По теореме Виета
х₁+х₂=-b/a
х₁*х₂=c/a
x²+12x-17=0
х₁+х₂= -12
х₁*х₂= -17
34-15x₂ 34 +13x₁ 34x₁-15x₂x₁ +34x₂+13x₁x₂ 34(x₁+x₂) -2 x₁*x₂
------------ + ---------------- = ------------------------------------- = ---------------------------
x₂ x₁ x₁*x₂ x₁*x₂
34*(-12) - 2 *(-17) (-17)*(-2)*(-12) - 2 *(-17) -17*(24-2)
-------------------------- = ---------------------------------- = ------------------ = 22
-17 -17 -17