(4mn^3+6m^3n)/(2n^2+3m^2)=2mn(2n^2+3m^2)/(2n^2+3m^2)=2mn[(2a-1)^2-(3a-1)^2]/(5a-2)={2a-1+3a-1)(2a-1-3a+1)/(5a-2)=-a(5a-2)/(5a-2)=-a解方程：(1)49x^2-25=0(7x+5)(7x-5)=0x1=-5/7x2=5/7所以原方程的解是：x...