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Prelim 2016 Maths Help Thread (3 Viewers)

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davidgoes4wce

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Q:

Two model rockets launched from two different launch pads G & D. From an observation site, O, rocket A has been launched at N28 degrees WEST and rocket B has been luanched at N40 degrees EAST. The angle of elevation from the observation location is 29 degrees for rocket A and 37 degrees for rocket B. If the distance between the observation site and launch pad G is 120m and the distance from observation site to a launch pad D is 80m, what is the distance between the two rockets AFTER THE LAUNCH.
Do you have an answer I just want to compare my answer?
 

InteGrand

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At the HSC level (since you don't know what a codomain is yet) a function is one-to-one iff every one value of x carries only ONE value for y.

If x and y happen to equal to the same thing that means jack shit. It's that for every x-value, there can be at most one y-value.

If x=0 then y=0 and y=1 SIMULTANEOUSLY then it's no longer one-to-one
This is essentially referring to the definition of a function (no input has more than two outputs).

For one-to-one, it's basically reverse: every y-value in the range has one and only one x-value in the domain. Or equivalently, we don't have two different x-values getting mapped to the same y-value.

For eyeseeyou's one, since no two different x-values map to the same y-value (as all the y-values are different), it's one-to-one.
 
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eyeseeyou

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Q:

Two model rockets launched from two different launch pads G & D. From an observation site, O, rocket A has been launched at N28 degrees WEST and rocket B has been luanched at N40 degrees EAST. The angle of elevation from the observation location is 29 degrees for rocket A and 37 degrees for rocket B. If the distance between the observation site and launch pad G is 120m and the distance from observation site to a launch pad D is 80m, what is the distance between the two rockets AFTER THE LAUNCH.
Unfortunately I do not. I got it from yahoo answers
 

eyeseeyou

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Might post some more inverse function Q's later tonight and tomorrow morning
 

eyeseeyou

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Can someone please help me with Induction (maths). I really suck at it

1. 1+2+3+...+n=(n(n+1))/2
2. 1/(x^n(x-1)=1/(x-1)-1/x-1/x^2-...-1/x^n
 

eyeseeyou

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3. 1^2+3^2+5^2+...+(2n-1)^2=((n(4n^2-1)/3)
4. 1.1!+2.2!+3.3!+...+n.n!=(n+1)!-1
 

eyeseeyou

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The steps i follow are

1. Show true for n=1 (or whenever it starts)
2. Assume true for n=k
3. Show true for n=k+1 (this step always annoys me) Always involve assumption
4. Conclusion

Using my 4 steps could you please help me
 

InteGrand

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The steps i follow are

1. Show true for n=1 (or whenever it starts)
2. Assume true for n=k
3. Show true for n=k+1 (this step always annoys me) Always involve assumption
4. Conclusion

Using my 4 steps could you please help me
All the steps are trivial here apart from 3. And I already helped you with 3.
 

eyeseeyou

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All the steps are trivial here apart from 3. And I already helped you with 3.
Yeah I think I know ths jist of things now

Anyways thanks

BTW when you answer my "why" science questions (phys and chem) could you please not say "By inspection" because it really annoys me. This is like...showing you have no pure knowledge to phys/chem at all
 

InteGrand

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Yeah I think I know ths jist of things now

Anyways thanks

BTW when you answer my "why" science questions (phys and chem) could you please not say "By inspection" because it really annoys me. This is like...showing you have no pure knowledge to phys/chem at all
You're welcome. :)
 
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