设a=(x+45)^(1/3),b=(16-x)^(1/3)则有a+b=1,a^3+b^3=45+16=61将b=1-a带入后式得a^3+(1-a)^3=61a^3+(1-a)^3=a^3-a^3+3a^2-3a+1=3a^2-3a+1=61a^2-a-20=0得a=5,-4则(x+45)^(1/3)=5,-4解得x=80,-109