Original post by Sonechka
Could someone help me with this? I'm pretty stuck :/
Make the subject first from the second equation before substituting in for it into the first equation.
Original post by zayn008
I would make a the subject of x
Then make t the subject of x
Sub them into the Y equation and simplify
Then make t the subject of x
Sub them into the Y equation and simplify
That would still give an equation for in terms of
I've got y = -ax^2 - 12a^2x + 8a but I'm not sure how to get that into the form the question asks for. Should I substitute 2at^1/2 in for x and then go from there?
Original post by Sonechka
I've got y = -ax^2 - 12a^2x + 8a but I'm not sure how to get that into the form the question asks for. Should I substitute 2at^1/2 in for x and then go from there?
That's wrong, post your working.
Original post by RDKGames
That would still give an equation for in terms of
you could sub in in terms of again to remove the 's from subbing in , but I'm guessing there's a better way
(edited 7 years ago)
Original post by zayn008
you could sub in in terms of again to remove the 's from subbing in , but I'm guessing there's a better way
Yeah you're taking a needless step by substituting in for .
Just express in terms of and sub that in and simplify as there wouldn't be any terms any more
Original post by RDKGames
That's wrong, post your working.
I accidentally found 2at^2 instead of 2at and then didn't write 4a*a as 4a^2 :s :s
Would it be ax^2 - 4a^2x - 2ax + 8a^2? That doesn't look right either but...
Original post by Sonechka
I accidentally found 2at^2 instead of 2at and then didn't write 4a*a as 4a^2 :s :s
Would it be ax^2 - 4a^2x - 2ax + 8a^2? That doesn't look right either but...
Would it be ax^2 - 4a^2x - 2ax + 8a^2? That doesn't look right either but...
That's wrong too. Post your working. You don't seem to be following what I've said in my first post...
Original post by RDKGames
That's wrong too. Post your working. You don't seem to be following what I've said in my first post...
t = x^2/4a^2
y = a(x^2/4a^2)^2 - 2a(x^2/4a^2)
= a(x^4/16a^4) - 2a(x^2/4a^2)
= ax^4/16a^5 - ax^2/4a^3
Is it ok up until there?
Original post by Sonechka
t = x^2/4a^2
y = a(x^2/4a^2)^2 - 2a(x^2/4a^2)
= a(x^4/16a^4) - 2a(x^2/4a^2)
= ax^4/16a^5 - ax^2/4a^3
Is it ok up until there?
y = a(x^2/4a^2)^2 - 2a(x^2/4a^2)
= a(x^4/16a^4) - 2a(x^2/4a^2)
= ax^4/16a^5 - ax^2/4a^3
Is it ok up until there?
Third line is fine, then your algebra mucks up. For example, as you do not multiply the denominator by
Original post by RDKGames
Third line is fine, then your algebra mucks up. For example, as you do not multiply the denominator by
Omg of course, what am I doing? Maybe doing maths at like half ten is a bad idea...
Anyway: ax^4/16a^4 - ax^2/2a^2?
Original post by Sonechka
Omg of course, what am I doing? Maybe doing maths at like half ten is a bad idea...
Anyway: ax^4/16a^4 - ax^2/2a^2?
Anyway: ax^4/16a^4 - ax^2/2a^2?
Looks good. One small step and you got the required form.
Original post by RDKGames
Looks good. One small step and you got the required form.
So then I just cancel the as? x^4/16a^3 - x^2/2a?
Original post by Sonechka
So then I just cancel the as? x^4/16a^3 - x^2/2a?
Yes
Original post by RDKGames
Yes
Thanks so much!
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