Đáp án + Giải thích các bước giải:
`a)` `8x+20=-1/2`
`<=>8x=-1/2-20`
`<=>8x=-1/2-40/2`
`<=>8x=-41/2`
`<=>x=(-41/2):8`
`<=>x=-41/16`
Vậy `S={-41/16}`
`b)` `2 + (x-5)/4=(4x-1)/6`
`<=>24/12+[3(x-5)]/12=[2(4x-1)]/12`
`=>24+3(x-5)=2(4x-1)`
`<=>24+3x-15=8x-2`
`<=>24+3x-15-8x+2=0`
`<=>-5x+11=0`
`<=>-5x=-11`
`<=>x=11/5`
Vậy `S={11/5}`
`c)` `x^2-1+2x(x-1)=0`
`<=>(x-1)(x+1)+2x(x-1)=0`
`<=>(x-1)(x+1+2x)=0`
`<=>(x-1)(3x+1)=0`
`<=>`\(\left[ \begin{array}{l}x-1=0\\3x+1=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=1\\x=-\dfrac{1}{3}\end{array} \right.\)
Vậy `S={1;-1/3}`
`d)` `1/(2x-3)-5/x=3/(2x^2-3x)(xne0,xne3/2)`
`<=>1/(2x-3)-5/x=3/[x(2x-3)]`
`<=>x/[x(2x-3)]-[5(2x-3)]/[x(2x-3)]=3/[x(2x-3)]`
`=>x-5(2x-3)=3`
`<=>x-10x+15=3`
`<=>-9x=-12`
`<=>-3x=-4`
`<=>x=4/3(tm)`
Vậy `S={4/3}`.
