`a,(x+3)^2(-6-2x)^3=0`
`<=>`$\left\{\matrix{(x+3)^2=0\hfill\ \cr (-6-2x)^3=0\hfill}\right.⇔\left\{\matrix{x+3=0\hfill\ \cr -6-2x=0\hfill}\right.⇔\left\{\matrix{x=-3\hfill\ \cr -2x=6\hfill}\right.⇔\left\{\matrix{x=-3\hfill\ \cr x=-3\ (TM)\hfill}\right.$
Vậy `x=-3`
`b,x/3+x/4=21/12`
`<=>(4x)/12+(3x)/12=21/12`
`<=>(4x+3x-21)/12=0`
`<=>7x-21=0`
`<=>7x=21`
`<=>x=3`
Vậy `x=3`
`c,(x-2)/5=(1-x)/6`
`<=>(6(x-2))/30+(5(x-1))/30=0`
`<=>(6x-12+5x-5)/30=0`
`<=>11x-17=0`
`<=>11x=17`
`<=>x=17/11`
Vậy `x=17/11`
`(x-3)/2=-8/(x-3)`
`<=>(x-3)^2/(2(x-3))+16/(2(x-3))`
`<=>x^2-6x+9+16=0(ko TM)`
Vậy không có nghiệm thỏa mãn pt
$#Blink$ $\boxed{\text{@Rosé}}$
