1.(n-6)(2n+3)-(n-7)в квадрате-(2+n)(n-2)
(n-6)(2n+3)-(n-7)²-(2+n)(n-2)= 2n²-12n-18+3n-(n²-14n+49)-(n²-4)= 2n²-12n-18+3n-n²+14n-49-n²+4= 5n-63