1.由题意可设需涨x元,则
(10+x)(500-20x)>=6000
---->(x+10)(x-25)x^2-15x-250x^2-15x+50(x-5)(x-10)5(1-x)(200+400x)>=224
---->(1-x)(1+2x)>=1.12
---->2x^2-x+0.12(2x-0.4)(x-0.3)0.2
1.由题意可设需涨x元,则
(10+x)(500-20x)>=6000
---->(x+10)(x-25)x^2-15x-250x^2-15x+50(x-5)(x-10)5(1-x)(200+400x)>=224
---->(1-x)(1+2x)>=1.12
---->2x^2-x+0.12(2x-0.4)(x-0.3)0.2