Find the sum of all real solutions for x to the equation (x2+2x+3)(x2+2x+3)(x2+2x+3)=2012.
A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.
Solution
When y=x2+2x+3, note that there is a unique real number y such that yyy=2012 because yyy is increasing in y. The sum of the real distinct solutions of the equation x2+2x+3=y is -2 by Vieta's Formulae as long as 22+4(y−3)>0, which is equivalent to y>2. This is easily seen to be the case; therefore, our answer is -2.
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