(X mũ 2 +1).(X-3)=0 X.(X+1)=0 X-28-(15+X)=-(23-X) 32-X-(-X+15)=(-21+X) Mn người giúp mk cần gấp chiều đi học ạ.

a) `(x²+1)(x-3)=0`

`⇒` \(\left[ \begin{array}{l} x²+1=0\\x-3=0\end{array} \right.\) 

`⇒` \(\left[ \begin{array}{l}x=∅\\x=3\end{array} \right.\) 

b) `x(x+1)=0`

`⇒` \(\left[ \begin{array}{l}x=0\\x+1=0\end{array} \right.\) 

`⇒` \(\left[ \begin{array}{l}x=0\\x=-1\end{array} \right.\) 

c) `x-28-(15+x)=-(23-x)`

`⇒ x-28-15-x+23-x=0`

`⇒ -x-20=0`

`⇒ -x=20`

`⇒ x=-20`

d) `32-x-(-x+15)=(-21+x)`

`⇒ 32-x+x-15=-21+x`

`⇒ -21+x=17`

`⇒ x=-21-17=-38`