its so easy 王心凌:初一数学习题,来帮帮我

来源:百度文库 编辑:高校问答 时间:2024/05/03 07:45:21
解不等式:
(5X-2)(2X-3)小于或等于(X+5)(10X-1)

(5x-2)(2x-3)<=(x+5)(10x-1)
10x^2-19x+6<=10x^2+49x-5
-19x+6<=49x-5
11<=68x
x>=11/68

乘除来,得-19x+6小于等于49x-5
68x大于等于11
x大于等于11/68

把原不等式乘出来,得-19x+6小于等于49x-5
68x大于等于11
x大于等于11/68

解:
(5x-2)(2x-3)<=(x+5)(10x-1)
10x^2-15x-4x+6<=10x^2-x+50x-5
10x^2-19x+6<=10x^2+49x-5
-19x+6-49x+5<=0
-68x+11<=0
-68x<=-11
x>=11/68

解:
(5x-2)(2x-3)≤(x+5)(10x-1)
先乘得:
10x^-15x-4x+6≤10x^-x+50x-5
移项得:
10x^-15x-4x-10x^+x-50x≤-5-6
合并同类项得:
-68x≤-11
x≥11/68