Question

 resolva as equações o 2¨grau 

 

x²+2x+1= 0

 

 

x²+20x= 300 

 

 

x²+5x= 6

Answer 1

a )

$x^2-2x+1=0\\\Delta=2^2-4.1.1\\\Delta=0\\ \\x= \frac{-b}{2a} ~\to~x=-1$

b )

$x^2+20x=300\\x^2+20x-300=\\\Delta=20^2-4.1.(-300)\\\Delta=1600$

$x= \frac{-20\pm \sqrt{1600} }{2} ~\to~ \frac{-20\pm40}{2} ~\to~x=-10\pm20$

$x'=10~~~~x''=-30$

c )

$x^2+5x=6\\x^2+5x-6=0\\\Delta=5^2-4.1.(-6)\\\Delta=49$

$x= \frac{-5\pm \sqrt{49} }{2} ~\to~x= \frac{-5\pm7}{2}$

$x'=1$

$x''=-6$