\(\begin{array}{l}b)\;3\sqrt {12} - 2\sqrt {27} + \sqrt {48} \\ = 3\sqrt {4.3} - 2\sqrt {9.3} + \sqrt {16.3} \\ = 3\sqrt {{2^2}.3} - 2\sqrt {{3^2}.3} + \sqrt {{4^2}.3} \\ = 3.2\sqrt 3 - 2.3\sqrt 3 + 4\sqrt 3 = 4\sqrt 3 .\end{array}\) Đề bài Rút gọn biểu thức : a) \(3\sqrt {32} + \sqrt {50} \); b) \(3\sqrt {12} - 2\sqrt {27} + \sqrt {48} \). Lời giải chi tiết \(\begin{array}{l}a)\;3\sqrt {32} + \sqrt {50} = 3\sqrt {16.2} + \sqrt {25.2} \\ = 3\sqrt {{4^2}.2} + \sqrt {{5^2}.2} \\ = 3.4\sqrt 2 + 5\sqrt 2 \\ = 12\sqrt 2 + 5\sqrt 2 = 17\sqrt 2 .\end{array}\) \(\begin{array}{l}b)\;3\sqrt {12} - 2\sqrt {27} + \sqrt {48} \\ = 3\sqrt {4.3} - 2\sqrt {9.3} + \sqrt {16.3} \\ = 3\sqrt {{2^2}.3} - 2\sqrt {{3^2}.3} + \sqrt {{4^2}.3} \\ = 3.2\sqrt 3 - 2.3\sqrt 3 + 4\sqrt 3 = 4\sqrt 3 .\end{array}\)
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