[tex]x^2+5x-300=0 \\ \\ \Delta =b^2-4ac =5^2 -4*1* (- 300)= 25+1200=1225 \\ \\x_{1}=\frac{-b- \sqrt{\Delta } }{2a}=\frac{-5- \sqrt{1225}}{2 }=\frac{-5-35}{2}=-\frac{-40}{2}=-20 \\\\ \ side \ not \ can \ also \ be \ negative[/tex]
[tex]x_{2}=\frac{-b+ \sqrt{\Delta } }{2a}=\frac{-5+ \sqrt{1225}}{2 }=\frac{-5+35}{2}=-\frac{30}{2}=15\\ \\Ansewr : \ x= 15[/tex]
