Odpowiedź:
[tex]x^2+18=9x\\\\x^2-9x+18=0\\\\a=1\ \ ,\ \ b=-9\ \ ,\ \ c=18\\\\\Delta=b^2-4ac\\\\\Delta=(-9)^2-4\cdot1\cdot18=81-72=9\\\\\sqrt{\Delta}=\sqrt{9}=3\\\\x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-3}{2\cdot1}=\frac{9-3}{2}=\frac{6}{2}=3\\\\x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+3}{2\cdot1}=\frac{9+3}{2}=\frac{12}{2}=6[/tex]
