VCE Methods Question Thread!

[usernameincorrect]

Quick question, can 'proportion', in a probability question be expressed as a percentage? For example, if the question was 'what proportion of the apples are red'?

[Shadowxo]

Quick question, can 'proportion', in a probability question be expressed as a percentage? For example, if the question was 'what proportion of the apples are red'?

It's convention to have proportion as between 0 and 1, but theoretically you could use a percentage as it represents the same thing. In tests/exams though I'd stick with 0-1 unless it specifies percentage

[Rieko Ioane]

But, if m=-1 then g(x)=1 and its inverse can't be found this way. Remember, the inverse is basically the function flipped around the line y=x so the inverse function would be x=1 (so technically isn't a function). There needs to be an x and y to switch around to find the inverse like that

For f), I would think you'd work the inverse out by hand and make w and w^-1 equal to find the coordinates. If it's a calculator test/exam though I wouldn't think they'd take marks off for it not being exact values unless they specified in the question.

Thanks.

I was looking over this and for part c) why do exclude m=0? I

[Shadowxo]

Thanks.

I was looking over this and for part c) why do exclude m=0? I

It's simply because "m and n are non-zero constants". Without that, m=0 would be valid

[Rieko Ioane]

It's simply because "m and n are non-zero constants". Without that, m=0 would be valid

Damn I'm an idiot...thanks!

[stunner05]

hey guys so the particular question i diidnt understand  was question 3 on the 2015 exam 2 multi choice. I get how the b can be negative so wouldnt the factor be (x+b)? I would add the pic but i'm just not that tech savy..ugh sigh legit suck at everything

[gnaf]

hey stunner05!

Try subbing in values for b, c and d!

If you let b= -1, c=2 and d=3, then the equation is a(x-(-1))(x-2)(x-3)
Since b is =1, the equation is in the form a(x-b)(x-c)(x-d)

[ZNormal]

Hi! I was just wondering what the derivative of 2/x was? I thought it was 2loge(x) but the answer for a Heffernan exam says -2x^-2, and how do you know when to differentiate to a log or normally?

Thank you in advance!

[gnaf]

Hi! I was just wondering what the derivative of 2/x was? I thought it was 2loge(x) but the answer for a Heffernan exam says -2x^-2, and how do you know when to differentiate to a log or normally?

Thank you in advance!

2/x is 2x^-1

To differentiate here, you drag down the power and subtract the existing power by 1
So the answer is -1* 2x^-2= -2x^-2

You get 2loge(x) by antidifferentiating

As far as I know in methods, you hardly ever get log as an answer by differentiating

[kiki.]

Hi, can someone explain how to figure out this question?

[Eric11267]

Hi, can someone explain how to figure out this question?

The question is asking you to find when the derivative is less than 0. So you need to find the points on the graph where the tangent has a negative gradient. The coordinates of the turning point will help you out, because the tangents to these points have gradients of 0

[kiki.]

Thank you Eric11267!

[kayalsingh]

Help solve this question please!!!

The normal to the curve with equation (a-x)^1/2 at x= b, where a and b are real constants and a > 0 and b < a, passes through the origin.
Find the value of b.

[Eric11267]

Help solve this question please!!!

The normal to the curve with equation (a-x)^1/2 at x= b, where a and b are real constants and a > 0 and b < a, passes through the origin.
Find the value of b.

Since the line passes through the origin, the equation of the normal line will be in the form y=mx+0
So you need to find the gradient of the normal line in terms of b, and then use the formula for deriving the normal line equation: y-y1=m(x-x1)
Then you'll have an equation that looks like y= mx+something, and the something needs to equal 0
I hope this helps, if its too ambiguous I can give you a worked solution

[chantelle.salisbury]

hello
i was talking to a friend who did methods a cpl of years ago and his teacher told his class that it is rare that students finish the exam in the allotted time.
is this true or is it just a fallacy?
would love to know