Given that, x 2 − b x + c = 0 and x = 2 − 1 2 + 1
Then, find the value of 1 + b + c .
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x = 2 − 1 2 + 1 2 + 1 2 + 1 = ( 2 + 1 ) 2 = 3 + 2 2 = 2 a b ± 2 a b 2 − 4 a c .
This gives b = 6 a and 8 = ( 2 a ) 2 b 2 − 4 a c = 9 − a c , meaning that c = a . All in all this gives us:
a x 2 − b x + c = a ( x 2 − 6 x + 1 )
and a + b + c = a + 6 a + a = 8 a . This is valid for any a ∈ R , hence as of yet this problem has no single solution. With the (in a way logical) choice of a = 0 however, we obtain a + b + c = 8 .
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As, x = 2 − 1 2 + 1
We get, x = 3 + 2 2
As, a x 2 − b x + c = 0 is a Binomial Equation, there have another root, x = 3 − 2 2
So, ( x − 3 − 2 2 ) ( x − 3 + 2 2 ) = 0
At last, x 2 − 6 x + 1 = 0
Compairing with, a x 2 − b x + c = 0 we get, a = 1 , b = 6 , c = 1
So, a + b + c = 1 + 6 + 1 = 8
I think, the question shouldn't be for only 10 points... But, what to do? :)