x(x+1)(3x+5y)=144x^2+4x+5y=24第二式x^2+x + (3x+5y) =243x+5y=24 - x^2 -x将3x+5y代入第一式x(x+1)(-x^2 - x +24) = 144-(x^2 +x)(x^2+x - 24)=144令 x^2+x=t-t(t-24)=144t^2-24t+144=0(t-12)^2=0所以t=12所以 x...