關於數學化簡題,怎麼從[1/(x+1)]*{(x-1)/(x+3)}+1]化簡到[1/(x+1)]*[2(X+1)/(X+3)],
[1/(x+1)]*{(x-1)/(x+3)}+1]
=[1/(x+1)]*{ [(x-1)+(x+3)] /(x+3)}
=[1/(x+1)]*[2(X+1)/(X+3)]
若-3<x<5,|x+3|-|x-5|化簡為全部
-3<x所以x+3>0,|x+3|=x+3
x<5所以x-5