help me please

Question

help me please

anonymous · Answer

if $$f(x)5x^3-2$$ and $$g(x)=x+1$$ find$$(f-g)(x)$$

anonymous · Answer

@mathstudent55 can you help me

anonymous · Answer

@zzr0ck3r can you help me when you get a moment

jhonyy9 · Answer

(f-g)(x) = 5x^2 -2 - (x+1) = ?

do you can calculi it now ?

anonymous · Answer

im still lost

e.mccormick · Answer

For reference:
$(f-g)(x)=f(x)-g(x)$
$(f+g)(x)=f(x)+g(x)$
$(f\cdot g)(x)=f(x)\cdot g(x)$
$(f\div g)(x)=f(x)\div g(x)$
$(f\circ g)(x)=f(g(x))$

So with yours, you are subtracting the entire g function from the f function.

e.mccormick · Answer

And Jonny, you changed a cube to a square.  Oops.

anonymous · Answer

so would it be $$5x^3+1$$

anonymous · Answer

because that is what i get when i would it out

e.mccormick · Answer

$f(x)=5x^3-2$
$g(x)=x+1$
$(f-g)(x)=f(x)-g(x)$
so
$(f-g)(x)=(5x^3-2)-(x+1)$

That is what johhy meant to do.

e.mccormick · Answer

Not sure how you are getting that.  Show the steps.

anonymous · Answer

nevermind because if you Simplify $$5x^3-2-x+1$$ it will be $$5x^3-x-3$$

e.mccormick · Answer

yah.  Now you have it.

anonymous · Answer

@e.mccormick hey how would you set it up if $$F(x)=x+6$$ and $$G(x)=x^4$$ what is $$G(F(x))$$

e.mccormick · Answer

$(f\circ g)(x)=f(g(x))$

This means that you take the one function and put it into the other.  Yours is the other way around:

$(g\circ f)(x)=g(f(x))$

So, if $f(x)=a+x$ and $g(x)=x^2$ then:

$(g\circ f)(x)=g(a+x)=(a+x)^2$

The f part is used to replace the x in the g part.  The us of ( ) around it helps keep things clear.  In the case of a power, the ( ) is absolutly required.