Решение
1) [(a - 7x)*a²] / [ax(a - 7x)] = a/x = - 6/10 = - 0,6
2) 10ab + 25a² - 10ab + b² = 25a² + b² = 25 + 4 = 29
3) [(a - 5x)*a²] / [ax(a - 5x)] = a/x = - 74/ - 10 = 7,4
4) 1/6x - (6x + y)/6xy = (y - 6x - y)/6xy = - 1/y = - 4
8) 8/x - 9/2x = (16 - 9)/ 2x = 7/2x = 7/(2*1,4) = 1/0,4 = 10/4 = 2,5
9) (a² - 81)/(2a² - 18a) = [(a - 9)*(a + 9)] / [2a*(a - 9)] = (a + 9)/2a =
= (1,5 + 9)/2*1,5 = 10,5 / 3 = 3,5