Mathematics Question Thread

[BPunjabi]

Well with gradient of tangent you differentiate.

So you make the equation first x^1/2 then differentiate. Then it becomes 1/2x^-1/2. Sub in x=4 and then find the gradient. Grad become 1/4 . With normal same principals but switch it around so repeat first steps.  Differentiate x^2+5 which is 2x. Sub in -2, making it =-4. Then put the reciprocal which is 1/4. Thats the grad of a normal

[RuiAce]

Hey! I feel like this would be really obvious but I'm struggling with a few questions like find the gradient of the tangent to the curve: y= square root of x at (4,2) and find the gradient of the normal to the curve y=x² + 5 at (-2,9)

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[BPunjabi]

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Rui I swear that the normal is the exact same method as tangent but you swap it to the reciprocal? Like in my method above^^

[RuiAce]

Rui I swear that the normal is the exact same method as tangent but you swap it to the reciprocal? Like in my method above^^

*Negative reciprocal

But yeah nothing I said really contradicts the main idea you posed

[BPunjabi]

*Negative reciprocal

But yeah nothing I said really contradicts the main idea you posed

No I just meant the second part because I thought you were alluding that the answer was -1. Had no idea what you were trying to say

[RuiAce]

No I just meant the second part because I thought you were alluding that the answer was -1. Had no idea what you were trying to say

I never said that. I said that two lines that are perpendicular have their gradients multiply to -1.

[BPunjabi]

I never said that. I said that two lines that are perpendicular have their gradients multiply to -1.

Oh I understand aha, Sorry for the confusion!!

[Alize]

Your answers should be close to WolframAlpha's exact answers

Oh ok, that makes a lot more sense, thank you!   

[asd987]

i need help with this question ty
sketch y=√x+5       for −4≤x≤4  and find its max and min values.    btw, the square root is over x+5, not just x

[RuiAce]

i need help with this question ty
sketch y=√x+5       for −4≤x≤4  and find its max and min values.    btw, the square root is over x+5, not just x

Use brackets to show that you meant y=√(x+5) in the future.

[wesadora]

This question. This was a 1998 2 unit paper... Was this part of the older syllabus or something? Cause nowadays they just ask us to do probability trees. I mean, tables of outcomes are pretty simple but do they even teach that....otherwise other people might be like wtf.

[RuiAce]

This question. This was a 1998 2 unit paper and I know I didn't get taught what the hell a table of possible outcomes is. Was this part of the older syllabus or something? Cause nowadays they just ask us to do probability trees.

It means to draw a table listing out every single outcome.

An outcome is something that can happen. So for example you can get 4 on the blue die and 2 on the pink.

It is to be interpreted literally.
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And once you have a table you can literally just count the number of favourable outcomes for your probability.

[wesadora]

Thanks haha, yeah figured it out but like what the ._.

[RuiAce]

You're not taught enumeration techniques in 2U so it is unreasonable to make you do part (ii) without the table.

That being said I don't believe that this sort of thing is applicable for questions in 2U that are not about dice rolls

[julzzz]

I can't do this maths question! Help please!

Differentiate p=2x+50/x with respect to x.
Find any stationary points on the curve and determine their nature.

Thanks