Odpowiedź:
[tex]a)\\\\4x^2-20x+25=0\\\\a=4\ \ ,\ \ b=-20\ \ ,\ \ c=25\\\\\Delta=b^2-4ac\\\\\Delta=(-20)^2-4\cdot4\cdot25=400-400=0\\\\x_{0}=\frac{-b}{2a}=\frac{-(-20)}{2\cdot4}=\frac{20}{8}=\frac{5}{2}=2\frac{1}{2}[/tex]
[tex]b)\\\\9x^2+6x+1=0\\\\a=9\ \ ,\ \ b=6\ \ ,\ \ c=1\\\\\Delta=b^2-4ac\\\\\Delta=6^2-4\cdot9\cdot1=36-36=0\\\\x_{0}=\frac{-b}{2a}=\frac{-6}{2\cdot9}=\frac{-6}{18}=-\frac{1}{3}[/tex]
[tex]c)\\\\x^2+x+\frac{1}{4}=0\ \ /\cdot4\\\\4\cdot x^2+4\cdot x+\not4\cdot\frac{1}{\not4}=0\\\\4x^2+4x+1=0\\\\a=4\ \ ,\ \ b=4\ \ ,\ \ c=1\\\\\Delta=b^2-4ac\\\\\Delta=4^2-4\cdot4\cdot1=16-16=0\\\\x_{0}=\frac{-b}{2a}=\frac{-4}{2\cdot4}=\frac{-4}{8}=-\frac{1}{2}[/tex]
[tex]x^2+x+\frac{1}{4}=0\\\\a=1\ \ ,\ \ b=1\ \ ,\ \ c=\frac{1}{4}\\\\\Delta=b^2-4ac\\\\\Delta=1^2-\not4^1\cdot1\cdot\frac{1}{\not4_{1}}=1-1=0\\\\x_{0}=\frac{-b}{2a}=\frac{-1}{2\cdot1}=-\frac{1}{2}[/tex]
