Question

Como que faz a questão 13?

Answer 1

f ( x )= 2x-9

g ( x ) =x²+5x + 3

f ( g (x))= g (x)

2 (g ( x))-9= g ( x)

g(x)-9 =0

x²+5x+3 -9=0

x²+5x -6=0

Δ=b²-4ac

Δ= ( 5 )² -4 .1 - 6

Δ= 25 + 24

Δ=49

x=-b +- √Δ/2a

x= -5 +-√49/2

x=-5 +- 7/2

x'= -5 +7/2

x'= 2/2

x'=1

x''= -5-7/2

x''=-12/2

x''= -6

Logo:

I 1 I + I -6I = 1 +6 =7