А) 5x^2 -30x +45 = 5(x^2 - 6x + 9) = 5*(x-3)*(x-3)
б) 5x^2 + 34x - 7 = 5*(x + 7)*(x - 0.2)
-34 +- sqrt(34^2 + 4*5*7)/10 = (-34 +- 36)/10 = -7 и 0.2
25x^2 - 10x + 1 = 25*(x - 0.2)^2
10 +- sqrt(100-100)/50 = 1\5
сокращаем, получаем
5*(x + 7)*(x - 0.2) / 25*(x - 0.2)^2 = (x + 7)/ 5*(x - 0.2)