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2012 Year 9 &10 Mathematics Marathon (3 Viewers)

kazemagic

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Re: 2012 Year 9 &10 Mathematics Marathon

Here's another question. Solve for x and y:
 

russ3l

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Re: 2012 Year 9 &10 Mathematics Marathon

whats the point of posting up such difficult questions? everyone just searches the 'hardest question' they can find in hope to challenge someone with it. I mean comeon...we are doing 4unit math questions ffs TT.TT
 

kazemagic

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Re: 2012 Year 9 &10 Mathematics Marathon

whats the point of posting up such difficult questions? everyone just searches the 'hardest question' they can find in hope to challenge someone with it. I mean comeon...we are doing 4unit math questions ffs TT.TT
lol that triangle question can be done just using pythagoras, ymcaec just did it the way that looked complicated by using the cosine rule.
And that simultaneous question, i remember that you need to use completing square method and that's pretty much it I think
 

zeebobDD

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Re: 2012 Year 9 &10 Mathematics Marathon

try my q, and are you sure thats 9&10:S
 

bluecrisps

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Re: 2012 Year 9 &10 Mathematics Marathon

another question (procrastinating from school maths hw lol)

b) i) 2x+y=36 (width of material)
Therefore y=36-2x (rearrange the equation)

ii) Area= length x height
= x x y
Sub Equation from B)i)
= x(36-2x)
= 36x x 2x^2
iii) Axis of symmetry= -b/2a
= -36/2(-2)
= -36/-4
= 9
This is the maximum value of x as it is the axis of symmetry for a parabola

iv) A=36x x 2x^2
= 36(9) -2(9)^2
= 329-162
= 167 cm2
 
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Re: 2012 Year 9 &10 Mathematics Marathon

try my q, and are you sure thats 9&10:S
yes

It might seem very HSC-like with the maximum/minimum stuff, but it's really just a simple application of quadratics in year 10

b) i) 2x+y=36 (width of material)
Therefore y=36-2x (rearrange the equation)

ii) Area= length x height
= x x y
Sub Equation from B)i)
= x(36-2x)
= 36x x 2x^2
iii) Axis of symmetry= -b/2a
= -36/2(-2)
= -36/-4
= 9
This is the maximum value of x as it is the axis of symmetry for a parabola

iv) A=36x x 2x^2
= 36(9) -2(9)^2
= 329-162
= 167 cm2
Correct :)

however there's a calculation error in the last few steps,

 

bluecrisps

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Re: 2012 Year 9 &10 Mathematics Marathon

yes

It might seem very HSC-like with the maximum/minimum stuff, but it's really just a simple application of quadratics in year 10



Correct :)

however there's a calculation error in the last few steps,

Oops, darned windows calc -_-
 

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