Question

f(x)=x^(3)+3x,
find each value
b. f(1/4)
c. f(√2)

Answer 1

(1/4)^3 + (3/4)
sqrt(2)^3 + 3*sqrt(2)

Answer 2

that took alot of work

Answer 3

\[\left( \sqrt{2} \right)^{3}\]+\[3\sqrt{2}\]right?

Answer 4

but pls can i see the working?

Answer 5

for the second one,
\[f(\sqrt{2})=(\sqrt{2})^3+3(\sqrt{2})\\=
2^{3/2}+3\times2^{1/2}\]

Answer 6

pls electrkid how do u work it?i need it in the squaroot form

Answer 7

i see
what \(f(\sqrt{2})\) means is, replace every "x" in f(x) by \(\sqrt{2}\).
and that is exactly what you do

Answer 8

follow?

Answer 9

yes

Answer 10

or better even,
\[
f(x)=x^3+3x^2
\]
factorize the "x"
\[f(x)=x(x^2+3)\\
f(\sqrt{2})=\sqrt{2}[(\sqrt{2})^2+3]\\=\sqrt{2}(2+3)\\=5\sqrt{2}\]

Answer 11

how do u simplify \[\left( \sqrt{2} \right)^{3}\]?

Answer 12

I did not have to.
I factored the "x"

Answer 13

but if you want to, then you can do this:
\[(\sqrt{2})^3=(\sqrt{2})^2(\sqrt{2})=2\sqrt{2}\]