Question

Dada a função f (X) = X2 - 9x + 20. Quais são as raízes dessa função? (a) X = 4 e X = - 5 (b)X = -4 e X =5 (c) X = 4 e X=5 (d) X = - 4 e X = 5

Answer 1

x^2-9x+20=0
delta=b^2-4ac
delta=(-9)^2-4.1.20
delta=81-80
delta=1
x=-b-/+ raiz de delta/2a
x=-(-9)-1/2.1
x=9-1/2
x=8/2
x=4
x=-(-9)+1/2.1
x=9+1/2
x=10/2
x=5
S={(4, 5)}
Letra C

Answer 2

a)=4.2-9.-5+20 -> 8+45+20  -> 53+20  -> =73
b)=-4.2-9.5+20 -> -8-45+20 -> -53+20 -> = -33
c)4.2-9.5+20 ->  8-45+20 -> -37+20 -> = -17
d)-4.2-9.5+20 -> -8-45+20 -> -53+20 -> = -73