Odpowiedź :
[tex]-5x^2+4x+1=0 \ \ |\cdot(-1)\\\\5x^2-4x-1=0\\\\a=5, \ b=-4, \ c=-1\\\\\Delta=b^2-4ac\rightarrow(-4)^2-4\cdot5\cdot(-1)=16+20=36\\\\\sqrt{\Delta}=\sqrt{36}=6\\\\x_1=\frac{-b-\sqrt{\Delta}}{2a}\rightarrow\frac{-(-4)-6}{2\cdot5}=\frac{4-6}{10}=\frac{-2}{10}=-0,2\\\\x_2=\frac{-b+\sqrt{\Delta}}{2a}\rightarrow\frac{-(-4)+6}{2\cdot5}=\frac{4+6}{10}=\frac{10}{10}=1[/tex]