Question

Dada a funcao f=IR>IR por f(x)=x2-2x-15 calcule

a) f(0)
b) f(3)
c)f(x)=0

Answer 1

 
 
 
 

 f(x)=x2-2x-15 calcule
a) f(0) = (0)^2 - 2(0) - 15 = 0 + 0 - 15 ==> - 15

b) f(3)  = (3)^2 - 2(3) - 15 = 9 + 3 - 15 ==> - 3

c)f(x)=0

 
x2-2x-15 = 0
Δ =  (-2)² -4.1.(-15) = 4+60= 64                          √64 = 8
  

x= 2+/-8 ==> x1 = 5  e x2 =  - 3
        2