分类：教育/科学-理工学科-数学
问题：解数学题题目在附件里，请看附件 
题目在附件里，请看附件
回答：一，解下列各题
1.
2/(x-1)≤3x+2
===> 3x+2-[2/(x-1)]≥0
===> [(3x+2)*(x-1)-2]/(x-1)≥0
===> (3x^2-x-4)/(x-1)≥0
===> (3x-4)(x+1)/(x-1)≥0
===> x≥4/3，或者-1≤x＜1

2.
4x^2+8x＜5
===> 4x^2+8x-5＜0
===> (2x+5)(2x-1)＜0
===> -5/2＜x＜1/2

3.
6/(x-3)＜3/(x+1)
===> 2/(x-3)＜1/(x+1)
===> [1/(x+1)]-[2/(x-3)]＞0
===> [(x-3)-2(x+1)]/[(x+1)(x-3)]＞0
===> (-x-5)/[(x+1)(x-3)]＞0
===> (x+5)/[(x+1)(x-3)]＜0
<==> (x+5)(x+1)(x-3)＜0
===> x＜-5，或者-1＜x＜3

二，已知[f(x+h)-f(x)]/h=？？？，不然题目意思不全呀！！