cho mk xin hay nhất nhé bạn
`a)(3x-1)(x+2)-3x(x+1)=8`
`=>3x^2+6x-x-2-3x^2-3x-8=0`
`=>2x-10=0`
`=>2x=10`
`=>x=5`
vậy `x=5`
`b)(x+2)/x=(x^2+5x+4)/(x^2+2x)+x/(x+2)`
`đkxđx#0;x#-2`
`<=>(x+2)^2/(x(x+2))=(x^2+5x+4)/(x(x+2))+(x^2)/(x(x+2))`
`=>x^2+4x+4=x^2+5x+4+x^2`
`<=>-x^2-1x=0`
`<=>-x(x+1)=0`
`<=>`\(\left[ \begin{array}{l}-x=0\\x+1=0\end{array} \right.\)`<=>` \(\left[ \begin{array}{l}x=0(loại)\\x=-1(tm)\end{array} \right.\)
vậy pt có nghiệm duy nhất `S{-1}`
`c)x(2x-1)+(1-2x)=0`
`=>2x^2-x+1-2x=0`
`=>2x^2-3x+1=0`
`=>(x-1)(x-1/2)=0`
`=>`\(\left[ \begin{array}{l}x-1=0\\x-\frac{1}{2}=0\end{array} \right.\) \(\left[ \begin{array}{l}x=1\\x=\frac{1}{2}\end{array} \right.\)
vậy pt có nghiệm duy nhất `S={1;1/2}`
bài `2`
`(2(x-3))/7-(x-5)/3>=(12x+4)/21`
`<=>(6(x-3))/21-(7(x-5))/3>=(12x+4)/21`
`=>6x-18-7x+35>=12x+4`
`=>-13x>=-13`
`=>x<=1`
