VCE Methods Question Thread!

[Toki]

How do you do this question?
Express the function f(x)= 6x-5/3x+1 in the form a+ b/x+c.

Thanks
BTW How do you write maths equations in?

[brightsky]

f(x) = (6x-5)/(3x+1) = 2(3x - 5/2)/(3x+1) = 2(3x + 1 - 7/2)/(3x+1) = [2(3x+1)-7]/(3x+1) = 2 - 7/(3x+1)

[soNasty]

thanks brightsky i'll try and suss the whole addition of ordinates thing out.

[Toki]

Thanks brightsky

However I don't get why [2(3x+1)-7]/3x+1 became 2- 7/(3x+1)

Your answer is right, but I was just wondering
Wouldn't it be 2/(3x+1) -7?

[BLACKCATT]

2(3x+1)-7/3x+1
= 2(3x+1)/(3x+1)  - 7/3x+1
= 2 - 7/(3x+1)

[Phy124]

how would i graph something like
y=|2x+1|+|2x-1|?

these modulus graphs are confusing ..

I think it's easiest to graph it in the way brightsky suggested but you can also write it out as a hybrid function and graph it from that. (I suppose it might be helpful to learn this in case you are asked to write something as a hybrid function, if they do that (?))

[soNasty]

Thank you so much I get it now!

[soNasty]

How would i find the x intercept of

y=(x-2)*2^(x-1)?

[lzxnl]

How would i find the x intercept of

y=(x-2)*2^(x-1)?

Is that ?

If so, then you just set the bracket (x-2)=0 to get x=2 by null factor law.

[soNasty]

Is that ?

If so, then you just set the bracket (x-2)=0 to get x=2 by null factor law.

yeah, oh really? how come? what about the ?
thanks btw

[Daenerys Targaryen]

You would do it asif you had

So



Which is undefined as cant log a 0

so the only solution is x=2

[eagles]

When finding for x-intercept we let y=0

So this means 2^x-1 multiply by (x-2) = 0.

One of the two terms must equal to zero for this to work.

Recall that the exponential graph has a horizontal asymptote at y=0, thus 2^x-1 can never equal to zero for any value of x.

Therefore, (x-2) = 0.  Using NFL, x=2.

[lzxnl]

You can't raise any number to a finite power and get zero. You just cannot.

I'll give a ridiculous proof that gives you an idea of why it doesn't work.
Assume b exists such that a^b=0 for some a.
Then, we have a^(-b)=+-infinity for that same b. (reciprocal)
That looks like a problem.

[soNasty]

thanks so much guys!

[Only Cheating Yourself]

Why did no one teach me this!!!! 
I need help with this question please.

Sharon is three times as old as her daughter.  If Sharon is 32 years old than her daughter, what are their ages?
My working out… Sharon=x Daughter=y

3x+y
32x

Thats all i can do, now what that looks like crap so i don't even know what to do this is pathetic!  This is a year 9 question.