1)3x(3x+7)-(3x+1)²=9x²+21x-9x²-6x-1=15x-1
2)(y-2)(y+3)-(y-1)²=y²+3y-2y-6-y²+2y-1=3y-7
3)(p+1)²-(p+2)²=p²+2p+1-p²-4p-4=-2p-3
4)3(2a-5b)²-12(a-b)²=12a²-60ab+75b²-12a²+24ab-12b²=-36ab+63b²
5)(3x²+4)²+(3x²-4)²-2(5-3x²)(5+3x²)=9x^4+24x²+16+9x^4-24x²+16-50+18x²=
=18x^4+18x²-18
50.000-1397.3=-1347.3
20.4+33.603=54.003
-1347.3:54.003=-24.948614
2х²+7х-4=0, D=81, x1=1/2 U x2=-4
2(x-1/2)(x+4)/(x-4)(x+4)=2(x-1/2)/x-4=2x-1/x-4