(x^2+2x-3)/(x^2+3x-10):(x^2+7x+12)/(x^2-9x+14)
(x^2+2*x-3)/(x^2+3*x-10)/(x^2+7*x+12)/(x^2-9*x+14) = 0
(x-1)/ (x-7)*(x-2)^2*(x+4)*(x+5)=0
x-1=0
x=1
ОТвет:1