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Really hard maths question

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You can't solve this algebraically as a stand alone question because there isn't enough information. You have to use some general knowledge and also assume that it's an integer solution and then use the trial and error already discussed. I do wonder where you found such a question..
edit: Actually I don't think you have to assume it is an integer because x^3 must be an integer, and then x is either an integer or irrational, and if it is irrational then 7x is irrational which is stupid, but I doubt you are expected to realise this given the level of the exam I have been shown this question is on..

so how would you work it out?

Reply 21

cipi

Not enough info to solve this - you need to know how old he was or the year he died. Answer should be 12 as he died at 84. But year was 1727 so it should be x^3-1, not x^3+1

Reply 22

math42

Original post by theBranicAc

so how would you work it out?

Basically trial and error on x given that you roughly know when he died. 10^3 should be your first port of call as it is the first that is four digits but this is clearly too small. 11^3 is too small also. 12^3 though, just right (though as pointed out above me factually speaking the question should say x^3 - 1) and indeed 13^3 will be much too large. Then you just do 12^3 + 1 - 7 * 12 to get the "answer" because this is his death year minus how long he lived so will give you when he was born

Reply 23

RDKGames

Study Forum Helper

As others said, you need general knowledge when he was born, the narrower the gap the better. You cannot solve directly because you have two unknowns, a cubic and not enough info.

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(edited 7 years ago)

Reply 24

an_atheist

Trial and error.
Just find the values of x^3+1 and 7x for all x p to say, 15. Then just compare them until you reach a somewhat realistic age and year of death, then find the difference

Reply 25

theBranicAc

Original post by RDKGames

As others said, you need general knowledge when he was born, the narrower the gap the better. You cannot solve directly because you have two unknowns, a cubic and not enough info.

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so if you had no idea when he was born then you wont be able to solve it?
because im pretty sure in an exam i wont remeber when he was born

and also how do you not know it could be a random year, just because it says issac newton it doesn't mean the year he was born would be similar to the question?

Reply 26

RDKGames

Study Forum Helper

Original post by theBranicAc

If you had no idea then yes you wouldn't be able to solve it. This is because Newton is the only hint the question gives for your answer, the cubic and the linear expression can give you literally any year for any random person. I suppose you can still get method marks for doing trial and error but without the knowledge of his period, those are the 4 marks that I'd happily sacrifice.

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Reply 27

RDKGames

Study Forum Helper

Original post by LionKing101

Firstly, I took X out of my willy and substituted 3Y from my bum (the reason it's 3Y is due to Newton's ribs and kidneys. This gives X + 3Y (bum + ribs)? Plus, a left pinky toe (which is green and blue in colour)

Hence, by ordering 2 zinger burgers from KFC from the year 2016, by ordering 2 zinger burgers (chicken), you times this by 2...

2016 x 2 = 2032

However, you still have bum + ribs (preferably donor)? Consequently,
2*(bum + ribs) = 4

2032 - 4 = 2028

But, there is still one more algebraic derivative left from pinky toe

Hence, you must minus by 1, this gives 2027

Final answer = 2027