(а+3)(а-5)>(а+5)(а-7)
a²-2a-15 > a²-2a-35
a²-2a-15-a²+2a+35 > 0
20 > 0
верно при любых значениях а
1/4 (cos(2 x)+cos(4 x)+cos(6 x)+1) = 1
12/x²-4 + 3/x+2 = 12/( (х+2)(х-2) ) + ( 3(х-2) ) / ( (х+2)(х-2) ) = (12 + 3х - 6) / ( (х+2)(х-2) ) = ( 3(х+2)) / ( (х+2)(х-2) ) = 3/(х-2) = 3/(3002-2) = 3/3000 = 0,001