1).7(x-3)-5(x+4)=9 2).9(x-6)-7(x+8)=0 3).11(x-2)-6(x+3)=20

1) 7( х - 3) - 5(х + 4) = 9;7х - 21 - 5х - 20 = 9;7х - 5х = 9 + 20 + 21;2 х = 50;х = 50 : 2 = 25.Проверка:7(25 - 3) - 5(25 + 4) = 9;7 ∙ 22 - 5 ∙ 29 = 9;154 - 145 = 9;9 = 9.2) 9( х - 6 ) - 7( х + 8 ) = 0;9х - 54 - 7х - 56 = 0;9х - 7х = 56 + 54;2 х = 110;х = 110 : 2 = 55.Проверка:9( 55 - 6 ) - 7( 55 + 8) = 0;9 ∙ 49 - 7 ∙ 63 = 0;441 - 441 = 0;0 = 0.3) 11( х - 2 ) - 6( х + 3 ) = 20;11 х - 22 - 6х - 18 = 20;11х - 6х = 20 + 18 + 22;5х = 60;х = 60 : 5 = 12.Проверка:11( 12 - 2 ) - 6 (12 + 3 ) = 20;11 ∙ 10 - 6 ∙ 15 = 20;110 - 90 = 20;20 = 20.