Posers and Puzzles
15 Jun 03
17 Jun 03
1 edit
I cannot see how you're supposed to prove that:
20x + x^2 = 400
However, it is possible to solve it, and find x (I suppose that's the purpose of this task):
20x + x^2 = 400
x^2 + 20x + 100 = 500
(x + 10)^2 = 500
x + 10 = [+/-]sqrt(500)
x = [+/-] 10sqrt(5) - 10
If you'd like, you can say:
x = 10([+/-]sqrt(5) - 1)
[+/-] -- plusminus-thingy (\pm in (La)TeX) 🙂
11 Jul 03
Originally posted by astevensonif you solve it, then you are proving it, are you not? but would that not be possible for any equation of that form? i.e. 463x+2x^2=547, albeit that x will not always be in interget...?
can someone help me here, this was in my GCSE maths paper and i didnt have a clue how to solve it..
prove that 20x + x squared = 400 (prove means u dont answer it im guessing)
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12 Jul 03
Originally posted by astevensonFor the wording of that question to make sense, they must have given you the value of X or made you work it out in an earlier part of the question.
can someone help me here, this was in my GCSE maths paper and i didnt have a clue how to solve it..
prove that 20x + x squared = 400 (prove means u dont answer it im guessing)