- 17 Jun '03 00:21 / 1 editI 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 12:42

if 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...?*Originally posted by astevenson***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) - 12 Jul '03 23:21

For 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.*Originally posted by astevenson***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)