Сократить дробь: 1) 5x-15 / x^2-9; 2) a^2+ab / ab; 3) 3a-a^2 / 2a-6; 4) 3a^2-7ab / ab

Сократить дробь:

1) 5x-15 / x^2-9 = [5 (x - 3) ]/[ (x - 3) (x + 3) ] = 5 / (x + 3) 2) a^2+ab / ab = [a (a + b) ]/ab = (a + b) / b 3) 3a-a^2 / 2a-6 = [a (3 - a) ]/[a (a - 3) ] = - 1 4) 3a^2-7ab / ab = [a (3a - 7b) ] / ab = (3a - 7b) / b