Respostas

2013-08-15T14:41:17-03:00
X²+x=90 
x²+x-90=0
A= 1 B= 1  C= -90
delta = 1² - 4.1.(-90)
delta = 1 - (-360)
delta = 1 + 360 = 361
 \frac{-1 + \sqrt{361} }{2 . 1}

 \frac{-1 + 19}{2}  \frac{18}{2} = 9 = x'

 \frac{-1 - 19}{2}  \frac{-20}{2} = -10 = x''