12x-5xa-5a+8x x=3 a=2 8x do potegi 2 +14 -25x do potegi 2- 3x -5 x=3

[latex]12x-5xa-5a+8x=12cdot 3-5cdot 3cdot2-5cdot 2+8cdot 3 =\ =36-30-10+24=oxed{20}[/latex] [latex]8x^2 +14 -25x^2- 3x -5=-17x^2-3x+9=-17cdot 3^2-3cdot 3+9=\ =-17cdot 9 -9+9=oxed{-153}[/latex]

x=3 a=2 12*3-5*3*2-5*2+8*3=36-30-10+24=20 x=3 8x²+14-25x²-3x-5= 8*3²+14-25*3²-3*3-5= 8*9+14-25*9-9-5= 72+14-225-14= -153