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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) 🙂
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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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)