The base for 221 is 3.
convert one Number into decimal Number and then with the base x, convert another Number into Decimal Number and equate them to find the value of x.
So, (25)10 = 2(10)+5+0
(221)x is in Decimal System.
Now, solving the equation
[tex]2x^2+2x+1 = 25\\2x^2+2x-24=0\\2x^2+8x-6x-24=0\\2x(x+4)-6(x+4)=0\\(2x-6)(x+4)=0\\2(x-3)(x+4)=0\\x=3,-4[/tex]
x=-4 is neglected as the base cannot be negative.
Thus the base for 221 is 3.
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