Question

If f(2x) - 16x^3 + 20x, then what is f(3x)?

Answer 1

do u mean
f(2x) = 16x^3 + 20x

Answer 2

ye

Answer 3

let
v=2x
x=v/2
then
f(v) - 16(v/2)^3 + 20(v/2)

Answer 4

typo
f(v) = 16(v/2)^3 + 20(v/2)

Answer 5

got the idea ?

Answer 6

so you would have
this function
f(v) = 16(v/2)^3 + 20(v/2)
find when v=3x :)

Answer 7

1. from f(2x), replace x by x/2 to get f(x)

2. from f(x), replace x by 3x to get f(3x)

or you could combine both the steps above to :

replace x by 3x/2 to get f(3x) from f(2x)

Answer 8

@hartnn how would it go, can u show me

Answer 9

go with easier method first...

find f(x) from f(2x)
by replacing all 'x' in f(2x) by 'x/2'

Answer 10

like if i say replace x by \(\heartsuit\) in f(2x)

you would do :
\(f (2\heartsuit) = 16\heartsuit^3 + 20 \heartsuit \)

Answer 11

similarly, replace
x by x/2 instead

Answer 12

54x^3+30x is final

Answer 13

\(\huge \checkmark \)

Answer 14

good work!