(x+y)t=(1.2x+y)·0.9t=(x+0.75y)(t+2.5),求t
问题描述:
(x+y)t=(1.2x+y)·0.9t=(x+0.75y)(t+2.5),求t
答
(x+y)t=(1.2x+y)*0.9t 可得y=0.8x
带入其中可得1.8xt=1.6xt+4x可得 t=20