Given, x = √3, what is (x + 1)² + (x − 1)² ?
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Correct answer: A
Explanation
Given:
x = √3
By the formula:
(a + b)² = a² + 2ab + b²
(a − b)² = a² − 2ab + b²
(x + 1)² + (x − 1)²
= (x² + 2x + 1) + (x² − 2x + 1)
= 2x² + 2
x = √3
= 2( (√3)² ) + 2
= 2(3) + 2
= 6 + 2
= 8