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Techmummy:

thank u so much

You're welcome.
You will be surprised most students will have 15% or 115% as their answers. A common mistake.

Techmummy:

Hi Anyone can help us to solve this problem

Mr.Neo s salary was decreased by 15% when his company was not doing well .
Now his company s financial situation has improved and his boss wants to restore his original salary .
By what % must his reduced salary be increased?
Thanks in advance

When company isn't doing well, Mr Neo salary was 85% of his original.

85% of his original --> 100% of current
100% of his original --> 100/85 * 100/1 = 117.647 % of current
Hence increase = 117.647 - 100 = 17.6% (correct to 3 sf)

To double check,
Let's set his original salary to $10,000
After reduction, he receives $8500
So, when his salary increased by 17.6%
117.647/100 * $8500 = $10,000.

anneshirleygilbert:

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Can someone pls help me with this question. I can do (i) and (ii). It's (iii) that I have trouble with.

TIA
Anne

Hi Anne,

I've done a video on a similar concept on finding ratio of triangles.
You can skip to 6 minutes to see the strategy in action.

Ai Ling, Ong

[youtube=http://www.youtube.com/watch?v=14Xi0DoyhfM][/youtube]

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lost boy:

Please help to solve question 2h and 3
Thanks
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slmkhoo:

Augmum:

Oic...i thot most schs would place order for their pupils...

Hope the agent quote u a better price than Popular...but, i wonder if the agent does sell to endusers ??

They didn't answer the phone today - I guess they're closed. Will try next week.

TI @ Bras Basah sells TI 84 Plus Pocket SE (most JC students are using this model) cheaper than Popular.

IB is likely to be TI nspire. It shows output in colours.

Eriskang:

Someone help with this question :rahrah: O-Level Additional Mathematics question on Maximum and Minimum Values on General Quadratic Functions (Quad Eqns, Inequalities, Modulus Fuctions).


Given that x² - 5x + 13 = (x - p)² + q for all real values of x, find the value of p and of q. Hence, state
(i) the minimum value of x² - 5x + 13,
(ii) the value of x at which the minimum value occurs
Sketch the curve y = x² - 5x + 13

No need for sketch. I'm so weak at mathematics I can't understand the questions at all :scratchhead:

x² - 5x + 13 = (x - p)² + q

p and q can be found by completing the square - shorter method but you must understand and remember the steps.
Another method is expansion and compare coefficient.
I have a video on sharing on the steps to completing the square.

Ai Ling

[youtube=http://www.youtube.com/watch?v=bf8PfyP2h74][/youtube]

Concept:

1)Perpendicular bisector of any chord passes through the centre of circle.
2) Equation of circle : (x-a)^2 + (y-b)^2 = r^2 where (x, y) is any point on circumference. (a,b) : centre of circle, r: radius.

To solve this qn I would suggest drawing a diagram.

We need centre and radius of circle.

How to find centre?
- By solving simultaneous eqn of the given line and the perpendicular bisector or chord AB. Why? Both lines pass through centre.

- How to find eqn of perpendicular bisector of AB? We need gradient and a point on this perpendicular bisector.

Apply gradient formula on point A and B.
Relationship between AB and perpendicular bisector is m1.m2=-1. m1: gradient of AB. m2: gradient of perpendicular bisector of AB.

Then apply midpoint formula to find midpoint of AB. Why? Only this midpoint lies on the perpendicular bisector of AB.
Hence eqn of perpendicular bisector is formed.

Centre can be obtained.

How to find radius?
Apply distance formula between coordinate of centre (found earlier) and Point A or B (preferred since coordinate of B is 'prettier)'.

mom-of-2:

Can any kind soul please help me with this question please :

Find the equation of the circle which passes through the points A(5,-3), B(0,6) and has its centre lying on the line 2x-3y-6=0

Thank you very much in advance !