1) (6х-7)^2-(5х+7)(5х-7)=36x^2-84x+49-(5x+7)*(5x-7)=36x^2-84x+49-(25x^2-49)=36x^2-84x+49-25x^2+49=11x^2-84x+49+49=11x^2-84x+98
2) у(у+6)^2-(у+1)(у-6)^2=y*(y^2+12y+36)-(y+1)*(y-6)^2=y^3+y^2*12+36y-(y+1)*(y^2-12y+36)=y^3+y^2*12+36y-(y^3-11y^2+24y+36)=y^2*12+36y+11y^2-24y-36=23y^2+36y-24y-36=23y^2+12y-36
1) (6х-7)^2-(5х+7)(5х-7)=36x^2-84x+49-(5x+7)*(5x-7)=36x^2-84x+49-(25x^2-49)=36x^2-84x+49-25x^2+49=11x^2-84x+49+49=11x^2-84x+98
2) у(у+6)^2-(у+1)(у-6)^2=y*(y^2+12y+36)-(y+1)*(y-6)^2=y^3+y^2*12+36y-(y+1)*(y^2-12y+36)=y^3+y^2*12+36y-(y^3-11y^2+24y+36)=y^2*12+36y+11y^2-24y-36=23y^2+36y-24y-36=23y^2+12y-36