1)(y - 3)(y + 3)=y²-9
2)(2x - 3y)(2x + 3y)=4x²-9y²
По формуле ( a+b )( a-b ) = a^2-b^2
( 0.9m^3+10 )( 0.9m^3-10 ) = 0.81m^6-100
Смотри........................
1)(a-1)(a+1)/(1-a)=-(a+1);
2)=(m-n)/(m-n)^2=1/(m-n);
3)=(x+1)^2/(x-1)(x+1)=(x+1)/(x-1);
4)=(a-1)(a+1)/(a-1)^2=(a+1)/(a-1)
(5-t)(-t-5)-(4+t)² = (-t)²-25-(16+8t+t²) = (-t)²-25-16-8t-t² = - 41 - 8t