For all values of x, f(x)=3x+k, where k is a constant Given that ff(3) = 7, find the value of k? PLEASE HELP

1 Answer
BillytheKid
Nov 6, 2017

Not sure if you made a typo here...
if meant F(3) = 7 , then F(3) = 3*3+k = 7 so k equals -2..

Explanation:

If however it meant #ff(3) = f(f(3))#, then:
#f(3) = f(3*3 + k)#,
#=>f(f(3)) = 3(3x+k) + k#
#=> f(f(3)) = 9x + 4k = 7#
# x=3#, therefore # 27+4k = 7#
#=> 20 + 4k = 0#
#=> k = -5#

hope this helps....???

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