Đáp án+Giải thích các bước giải:
`d)|3x+1|=|x+3|`
`<=>[(3x+1=x+3),(3x+1=-x-3):}`
`<=>[(2x=2),(4x=-4):}`
`<=>[(x=1),(x=-1):}`
Vậy `S={1;-1}.`
`e)|x+5|+|x^2-25|=0`
`<=>|x+5|=-|x^2-25|`
Do `{(VT>=0),(VP<=0):}`
`<=>VT=VP=0`
`<=>{(x+5=0),(x^2-25=0):}`
`<=>{(x=-5),(x^2=25):}`
`<=>{(x=-5),([(x=5),(x=-5):}):}`
`<=>x=-5`
Vậy `S={-5}.`
`f)(x-1)^2=x^2`
`<=>(x-1)^2-x^2=0`
`<=>(x-1-x)(x-1+x)=0`
`<=>-1(2x-1)=0`
`<=>2x-1=0`
`<=>2x=1`
`<=>x=1/2`
Vậy `S={1/2}.`
