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數-代數 (9)-代數式b

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√( k - 13 ) = √a + √a √k + √a = √( 2k + a - √k ) a=? k=? I want step. 更新: Good!!!!!

最佳解答:

√( k - 13 ) = √a + √a.........(1) √k + √a = √( 2k + a - √k )............(2) From(1): √( k - 13 ) = √a + √a √(k - 13) = √(4a) k - 13 = 4a k = 4a + 13......(3) From (2): k + a + 2√(ka) = 2k + a - √k 2√(ka) = k - √k 4ka = k^2 + k - 2k√k 4a = k + 1 - 2√k (Since k is not = 0,because√(0-13) ) sub (3) to it : 4a = (4a+13)+1 - 2√(4a+13) 0 = 14 - 2√(4a+13) √(4a+13) = 7 4a+13 = 49 a = 9 k = 4*9 + 13 = 49

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