是4^x+6^x=6*9^x吧?
两边同除以9^x:(4/9)^x+(6/9)^x=6
即(2/3)^2x+(2/3)^2-6=0
[(2/3)^x+3][(2/3)^x-2]=0
因(2/3)^x>0
所以只能取(2/3)^x=2
故x=log(2/3) 2=ln2/(ln2/3)谢谢 答案是log(2/3)2