(6а-7+4а-3)(6а-7-4а+3)=(10а-10)(2а-4)=10*2(а-1)(а-2)=20(а-1)(а-2)
(x²-4)/(x²(x+3)-4(x+3))=0
(x²-4)/(x²-4)(x+3)=0
ОДЗ: x≠2, x≠-2, x≠-3
1/(x+3)≠0
x∈∅
(x²-3x-10)/(x-5)=0
ОДЗ: x≠5
(x²-5x+2x-10)/(x-5)=0
(x-5)(x+2)/(x-5)=0
x+2=0
x= -2
ctg1°*ctg2°*ctg3°*...*ctg179°=ctg1°*ctg2°*ctg3°*...*ctg90°...*ctg179°=0
(m-4)²|7n * 21n|m-4=3(m-4)