SOLUTION: 2. When the sum of 3 and twice a positive number is subtracted from the square of the number, the result is 0. Find the number. Show clear solution thanksss!

Question 1172177: 2. When the sum of 3 and twice a positive number is subtracted from the square of the number, the result is 0. Find the number. Show clear solution thanksss!
Found 2 solutions by Cromlix, math_helper:
Answer by Cromlix(4381) (Show Source): You can put this solution on YOUR website!
Hi there,
Making x the positive number
x^2 - 3 + 2x = 0
Rearrange
x^2 - (2x - 3) = 0
x^2 - 2x + 3 = 0
Factorise
(x + 1)(x - 3) = 0
x + 1 = 0
x = -1
x - 3 = 0
x = 3 (Disregard as negative)
x = 3 is the answer.
Hope this helps :-)
Answer by math_helper(2461) (Show Source): You can put this solution on YOUR website!

Saw an error in tutor Cromlix' answer, so came in to show the fix:

The expression should be:
, leading to...

x=3 and/or x=-1
Keeping just the positive answer,
--------------------------------
Tutor Cromlix tried to fix his answer, and while he arrives at the correct answer of x=3 this time, his steps still contain several errors:

Hi there,
Making x the positive number
x^2 - 3 + 2x = 0 <<< should be x^2 - 3 - 2x = 0
Rearrange
x^2 - (2x - 3) = 0
x^2 - 2x + 3 = 0
Factorise
(x + 1)(x - 3) = 0 <<< this is NOT the correct factorization of x^2-2x+3, rather is is the correct factorization of x^2-2x-3
x + 1 = 0
x = -1
x - 3 = 0
x = 3 (Disregard as negative) <<< left over from before his edits (??)
x = 3 is the answer. <<< yes, correct
Hope this helps :-)

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