Consider the function f(x) = 3x. which statement must be true?
a)
f(3)
f(1)
=
f(6)
f(4)
b) f(3)·f(1) = f(6)·f(4)
c) f(3) − f(1) = f(6) − f(4)
d) f(3) − f(1) = f(−3) − f(−1)

ANSWER

C)f(3) − f(1) = f(6) − f(4)

EXPLANATION

The given function is f(x)=3x

f(3)=3(3)=9

f(1)=3(1)=3

f(3)-f(1)=9-3=6

Also,

f(6)=3(6)=18

f(4)=3(4)=12

f(6)-f(4)=18-12=6

Therefore the correct choice is

C)f(3) − f(1) = f(6) − f(4)

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