Question

数学好的帮帮我

1.-x方—2x+15>0 2.-x方+x+12<0 3.|3x+4|大于等于1 4.|2x+1|<6 5.|4-5x |<1 这5道题怎么解不等式啊 very感谢

Answer 1

1.x^2+2x-15<0即(x+1)^2-16<0即(x+1)^2<16即
-4<x+1<4即-5<x<3
2.x^2-x-12>0即(x-1/2)^2-49/4>0即x-1/2>7/2
或x-1/2<-7/2即 x>4或x<-3
3.|3x+4|≥1即3x+4≥1或3x+4≤-1即x≥-1
或x≤-5/3
4.-6<2x+1<6即-7/2<x<5/2
5.-1<4-5x<1即-5<-5x<-3即3<5x<5即3/5<x<1