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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 9: câu 1; (3√8 – 4√2 + √40 ) √2 – √180 câu 2 ; √20 + √125 – √80 câu 3 ; 3√72 + √200 + 9√2 – 5√50 câu 4; 3√3+ 4√12 –

Toán Lớp 9: câu 1; (3√8 – 4√2 + √40 ) √2 – √180 câu 2 ; √20 + √125 – √80 câu 3 ; 3√72 + √200 + 9√2 – 5√50 câu 4; 3√3+ 4√12 – 5√27

Comments ( 2 )

  1. 1) (3\sqrt{8}-4\sqrt{2}+\sqrt{40})\sqrt{2} – \sqrt{180}
    = (6\sqrt{2}-4\sqrt{2}+\sqrt{40})\sqrt{2} – \sqrt{180}
    = (2\sqrt{2}+2\sqrt{10})\sqrt{2} – \sqrt{180}
    = 2(\sqrt{2})^2 + 2\sqrt{10}\sqrt{2} – \sqrt{180}
    = 4 + 2\sqrt{20}- 6\sqrt{5}
    = 4 + 4\sqrt{5} – 6\sqrt{5}
    = 4 – 2\sqrt{5}
    2) \sqrt{20} + \sqrt{125} – \sqrt{80}
    = 2\sqrt{5} + 5\sqrt{5} – 4\sqrt{5}
    = (2+5-4) \sqrt{5}
    = 3 \sqrt{5}
    3) 3\sqrt{3}+ 4\sqrt{12} – 5\sqrt{27}
    = 3\sqrt{3}+ 8\sqrt{3} – 15\sqrt{3}
    = (3+8-15) \sqrt{3}
    = – 4 \sqrt{3}

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222-9+11+12:2*14+14 = ? ( )