Question

dada a funcao f(x)=x²-4x-12, determine os valores reais de x para que se tenha:
a) f(x)=-15
b) f(x)=0

Answer 1

a ) x2 - 4x - 12 = - 15

x2 - 4x - 12 + 15 = 0

x2 - 4x + 3 = 0

∆ = 16 - 12

∆ = 4

X1 = ( 4 + 2 ) / 2

X1 = 3

X2 = ( 4 - 2 ) / 2

X2 = 2 / 2

X2= 1

b) x2 - 4x - 12 = 0

∆ = 16 + 48

∆ = 64

X1 = ( 4 + 8 ) / 2

X1 = 12 / 12

X1 = 1

X2 = ( 4 - 8 ) 2

X2 = - 4 / 2

X2 = - 2