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March 29, 2024, 01:47:56 am

Author Topic: Mathematics Question Thread  (Read 1296749 times)  Share 

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michaelalt

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Re: Mathematics Question Thread
« Reply #1755 on: April 27, 2017, 06:39:17 pm »
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I get it!! Tysm!

jamonwindeyer

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Re: Mathematics Question Thread
« Reply #1756 on: April 27, 2017, 07:58:05 pm »
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Thanks Jamon you f*&king Legend! You guys are awesome and amazing.

BTW for c) the answer would be -0.00128 right?

No worries! And not quite, so what the question wants is for you to be substituting values of \(t\) to guess how long it takes for the quantity to half. What this means is, estimate when:



So just try values of \(t\) and find the one that puts us closest to being true. It should be close to Jake's actual answer of 542 (which is a rounded answer, so in fact, your guess and check answer could also be 542 :) )

itssona

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Re: Mathematics Question Thread
« Reply #1757 on: April 27, 2017, 09:20:17 pm »
+1
heeey please help

x^2 + kx + 25 is a perfect square

what are the values for k


so i tried using the completing the square formula and I did x^2 + kx + (k/2)^2 = -25 + (k/2)^2 but im kinda stuck now :/
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jamonwindeyer

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Re: Mathematics Question Thread
« Reply #1758 on: April 27, 2017, 09:24:10 pm »
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heeey please help

x^2 + kx + 25 is a perfect square

what are the values for k


so i tried using the completing the square formula and I did x^2 + kx + (k/2)^2 = -25 + (k/2)^2 but im kinda stuck now :/

Hey! So if the quadratic is a perfect square, that is another way of saying there is only one root ;D we use the discriminant, for one root we need \(\Delta=0\):



Does that help? ;D

Shadowxo

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Re: Mathematics Question Thread
« Reply #1759 on: April 27, 2017, 09:29:57 pm »
+1
heeey please help

x^2 + kx + 25 is a perfect square

what are the values for k


so i tried using the completing the square formula and I did x^2 + kx + (k/2)^2 = -25 + (k/2)^2 but im kinda stuck now :/

Perfect square means it can be written as (a+b)2 or (a-b)2. in this case a=x and b=5
So 2ab=2*x*5=10x is equal to kx
k=10
or -2ab=-2*x*5=-10x is equal to kx
k=-10

Alternatively, if you had to show / prove it you might say
(k/2)2 = 25 and end up with the same result
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itssona

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Re: Mathematics Question Thread
« Reply #1760 on: April 27, 2017, 10:08:20 pm »
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Hey! So if the quadratic is a perfect square, that is another way of saying there is only one root ;D we use the discriminant, for one root we need \(\Delta=0\):



Does that help? ;D

oh!! I like this method, thank you Jamon!! It makes sense now :D

Perfect square means it can be written as (a+b)2 or (a-b)2. in this case a=x and b=5
So 2ab=2*x*5=10x is equal to kx
k=10
or -2ab=-2*x*5=-10x is equal to kx
k=-10

Alternatively, if you had to show / prove it you might say
(k/2)2 = 25 and end up with the same result

Thank you for showing this method too!! The concept is clearer now thanks to you and Jamon :) Thank you!

Mod Edit: Post merge :)
« Last Edit: April 27, 2017, 10:11:10 pm by jamonwindeyer »
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itssona

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Re: Mathematics Question Thread
« Reply #1761 on: April 27, 2017, 10:31:35 pm »
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hey quick easy one but,

my sheet said the answer is 2??? in the solutions

isnt it 4
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RuiAce

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Re: Mathematics Question Thread
« Reply #1762 on: April 27, 2017, 10:35:44 pm »
+1
hey quick easy one but,

my sheet said the answer is 2??? in the solutions

isnt it 4

I disagree with both sources

jamonwindeyer

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Re: Mathematics Question Thread
« Reply #1763 on: April 27, 2017, 10:37:07 pm »
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I disagree with both sources

It's the average of the two...


itssona

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Re: Mathematics Question Thread
« Reply #1764 on: April 27, 2017, 11:04:12 pm »
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I disagree with both sources

oh!!! okay thanks :D i get it hmm

It's the average of the two...
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« Last Edit: April 27, 2017, 11:05:34 pm by jamonwindeyer »
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michaelalt

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Re: Mathematics Question Thread
« Reply #1765 on: April 28, 2017, 09:56:33 am »
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Hi can someone help me with these? Q, 4 + 5, I've attached my diagrams + working. The correct answers are 4. 1343622km 5. 7367m
Thanks!

jamonwindeyer

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Re: Mathematics Question Thread
« Reply #1766 on: April 28, 2017, 11:09:36 am »
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Hi can someone help me with these? Q, 4 + 5, I've attached my diagrams + working. The correct answers are 4. 1343622km 5. 7367m
Thanks!

Hey Michael! Your only mistake is taking the given angles in degrees, they are in minutes! That little dash is the sign for minutes, so your angle for question four is \(0^\circ15'30''\)! The second one is \(0^\circ3'30''\) - You can also use decimals in the minutes place ;D

mcheema

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Re: Mathematics Question Thread
« Reply #1767 on: April 28, 2017, 07:17:00 pm »
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Can someone please help me with this question

mcheema

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Re: Mathematics Question Thread
« Reply #1768 on: April 28, 2017, 07:20:52 pm »
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Also can I get help with this one, my answer is close to the one in the answers but I cant seem to figure out where I made the mistake.

RuiAce

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Re: Mathematics Question Thread
« Reply #1769 on: April 28, 2017, 07:56:57 pm »
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Also can I get help with this one, my answer is close to the one in the answers but I cant seem to figure out where I made the mistake.



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