Đáp án+Giải thích các bước giải:
`a)|3-x|+x^2-(x+4)=0`
`<=>|3-x|=-x^2+x+4(-x^2+x+4>=0)`
`<=>[(3-x=-x^2+x+4),(3-x=x^2-x-4):}`
`<=>[(x^2-2x-1),(x^2-1=0):}`
`<=>[((x-1)^2=2),(x^2=1):}`
`<=>[(x=sqrt2+1(tm)),(x=-sqrt2+1(tm)),(x=1(tm)),(x=-1(tm)):}`
`b)|2x-1|=2x-1`
`<=>2x-1>=0`
`<=>2x>=1`
`<=>x>=1/2`
`=>S={x|x>=1/2}`
`c)x(2x-1)-8<5-2x(1-x)`
`<=>2x^2-x-8<5-2x+2x^2`
`<=>-x-8<5-2x`
`<=>x<-3`
`=>S={x|x<-3}.`
