Question

x sobre 2 menos x menos 20 igual a zero

Answer 1

a=1 b= -1 c= -20
delta: b2-4.a.c
(-1)2- 4.1. (-20)
1+80
81

x= -b+\- raiz quadrada de delta
--------------------------------------
2.a
x= -(-1) +\- raiz de 81
--------------------------------
2.1
x= 1+\- 9
-------------
2
x1= 10
----------- = 5
2

x2= -8
----------- = -4
2
s {5, -4}