a) x-9√x+14=0
⇔ x-7√x-2√x+14=0
⇔ √x(√x-7)-2(√x+7)=0
⇔ (√x+7)(√x-2)=0
⇔ \(\left[ \begin{array}{l}√x+7=0\\√x-2=0\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}√x=-7(vô lí)\\√x=2\end{array} \right.\)
⇔ x=4
Vậy x=4
b)√(x²-10x+25)=7-2x
⇔√(x-5)^2=7-2x
⇔ x-5=7-2x
⇔ x+2x=7+5
⇔ 3x=12
⇔ x=4
vậy x=4