(36x²+84x+49)(3x²+7x+4)=6,令3x^2+7x+4=t,则36x^2+84x+49=12t+1,原方程成为(12t+1)t=6,12t^2+t-6=0,∴t²+t/12-1/2=0（t+1/24）²=289/576∴t+1/24=±17/24∴t=2/3或-3/4当t=2/3时,3x^2+7x+4=2/3...