Question

dada a função f(x)=7x+2, determine:
a) f(-1) . f(3)=
b) f(2) / f(0)=
c) x para que f(x)=9
d) x para que f(x) = 72

Answer 1

a)
f(-1)=7.(-1)+2=-7+2=-5
f(3)=7.3+2=21+2=23

f(-1).f(3)= -5.23=-115

b)
f(2)=7.2+2=14+2=16
f(0)=7.0+2=0+2=2

f(2)/f(0)=
16/2
8

c)f(x)=9
7x+2=9
7x=9-2
7x=7
x=7/7
x=1

d)f(x)=72

7x+2=72
7x=72-2
7x=70
x=70/7
x=10