What is the sum of all the x 's that satisfy the equation below? x 2 − x − 1 0 x 2 − x − 1 1 = 2 2
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Why would you reject y = -1, since y = -1 Comes out to be x2-x-12 = 0
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y = x 2 − x − 1 1 , when y = − 1 , x 2 − x − 1 1 = − 1 is not real.
Consider x^2 -x-11 = A , Substituting the A in the Given Equation we get :-
New Equation :- A^2 -10A + 11=0 The value of A would be { (10 + Sqrt(56))/2 , (10 - Sqrt(56))/2) } = Real Number Let's say 'N'.
Putting the Value of A we get :-
Now x^2 -x-11 = N => x^2 -x -(11+N) =0
The Summation of Roots is -b/a for a Equation ax^2 + bx + c = 0..
So the sum of the Roots of x is [ - ( -1) / 1] = 1 (Ans)
equaltion:
x^{2} -x-11 -10*\sqrt(x^{2} -x-11) + 5^{2}=36
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x 2 − x − 1 0 x 2 − x − 1 1 x 2 − x − 1 1 + 1 1 − 1 0 x 2 − x − 1 1 y 2 + 1 1 − 1 0 y y 2 − 1 0 y − 1 1 ( y + 1 ) ( y − 1 1 ) ⇒ y ⇒ x 2 − x − 1 1 x 2 − x − 1 3 2 = 2 2 = 2 2 Let y 2 = x 2 − x − 1 1 = 2 2 = 0 = 0 = { − 1 1 1 Rejected since x 2 − x − 1 1 ≥ 0 Accepted = 1 1 2 = 0
By Vieta's formulas, the sum of roots of x is 1 .