Answer :
You first have to factor and get (x-8)(x+13)=o and set them equal to zero x-8=0 x=8 x+13=0 x=-13
[tex]x^2+5x-104=0\\\\a=1;\ b=5;\ c=-104\\\\\Delta=b^2-4ac;\ if\ \Delta > 0\ then\ x_1=\frac{-b-\sqrt\Delta}{2a};\ x_2=\frac{-b+\sqrt\Delta}{2a}\\\\\Delta=5^2-4\cdot1\cdot(-104)=25+416=441;\ \sqrt\Delta=\sqrt{441}=21\\\\x_1=\frac{-5-21}{2\cdot1}=\frac{-26}{2}=-13;\ x_2=\frac{-5+21}{2\cdot1}=\frac{16}{2}=8\\\\Answer:x=-13\ or\ x=8.[/tex]
