a, 210-5.(x-1) ²=-290
⇒ 5. (x-1)² = 210 - (-290) = 210 + 290
⇒ 5.(x-1)² = 500
⇒ (x-1)² = 100
⇒ \(\left[ \begin{array}{l}x-1=10\\x-1=-10\end{array} \right.\)
⇒ \(\left[ \begin{array}{l}x=11\\x=-9\end{array} \right.\)
Vậy x ∈ {11 ; -9}
b, 41-2.|23-x|=37
⇒ 2.|23 - x| = 41 - 37
⇒ 2.|23 - x| = 4
⇒ |23 - x| = 2
⇒ \(\left[ \begin{array}{l}23-x=2\\23-x=-2\end{array} \right.\)
⇒ \(\left[ \begin{array}{l}x=21\\x=25\end{array} \right.\)
Vậy x ∈ {21 ; 25}
