An algebra problem by Gourav Kushwaha

Algebra Level 3

Then Sum of all real possible value of x :-


The answer is 1.

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1 solution

Kartik Sharma
Oct 7, 2014

( x 4 + x 2 + 1 ) ( x 2 + x + 1 ) = 7 \frac{({x}^{4}+{x}^{2}+1)}{({x}^{2}+x+1)} = 7

Now, we can write numerator as x 4 + 2 x 2 + 1 x 2 {x}^{4}+2{x}^{2}+1 - {x}^{2}

= ( x 2 + 1 ) 2 x 2 {({x}^{2}+1)}^{2} - {x}^{2}

= ( x 2 + 1 x ) ( x 2 + 1 + x ) ({x}^{2} + 1 - x)({x}^{2} + 1 + x)

Now, the fraction can be written as -

( ( x 2 + 1 x ) ( x 2 + 1 + x ) ) ( x 2 + x + 1 ) = 7 \frac{(({x}^{2}+1-x)({x}^{2}+1+x))}{({x}^{2}+x+1)} = 7

x 2 + 1 x = 7 {x}^{2}+1-x = 7

x 2 x 6 = 0 {x}^{2} - x - 6 = 0

( x 3 ) ( x + 2 ) = 0 (x-3)(x+2) = 0

Therefore, x = 3, -2.

Hence, SUM = 3 -2 = 1

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