If (6 + 7√2)² = 134 + K√2, then what is the value of K?
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Correct answer: A
Explanation
Given:
(6 + 7√2)² = 134 + K√2
According to the formula:
(a + b)² = a² + 2ab + b²
(6 + 7√2)² = 6² + 2×6×7√2 + (7√2)²
= 36 + 84√2 + 49×2
= 36 + 84√2 + 98
= 134 + 84√2
K = 84