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What base? (Posted on 2022-05-28) Difficulty: 3 of 5
What base will make the bold text true:

Equation: 3x2-25x+66=0
It’s solutions x1=4 and x2=9 ?

Provide your reasoning.

No Solution Yet Submitted by Ady TZIDON    
Rating: 4.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Puzzle Solution | Comment 1 of 3
Let the base be n.
Then, the given equation is:
3x^2 -(2n+5)x +(6n+6) = 0 ......($) 

Since 4 is a root of the given equation, we substitute x=4 in ($) to obtain:
48-4(2n+5) +(6n+6)=0
=> 48 - 2n -14 =0
=> 2n=34
=> n=17

Accordingly,  the required base seems to be 17.
So, for n=17, the equation ($) reduces to;
3x^2 - 39x+108=0 .....(#) 
=> 3(x-4)(x-9)=0
=> x=4, 9
So, the two roots checks as x1=4 and x2=9 in full conformity with the provisions of the given problem.
 Consequently,  the required base is INDEED 17.


  Posted by K Sengupta on 2022-05-28 07:14:06
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