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

Toán Lớp 9: Thực hiện phép tính: a, 5√18 – √50 + √8. b, (2√6 + √5).(2√6 – 5). c, (√20 – 3√10 + √5).√5 + 15√2.

Toán Lớp 9: Thực hiện phép tính:
a, 5√18 – √50 + √8.
b, (2√6 + √5).(2√6 – 5).
c, (√20 – 3√10 + √5).√5 + 15√2.

Comments ( 2 )

  1. a) 5\sqrt{18}-\sqrt{50}+\sqrt{8}
    =5\sqrt{9.2}-\sqrt{25.2}+\sqrt{4.2}
    =15\sqrt{2}-5\sqrt{2}+2\sqrt{2}
    =12\sqrt{2}
    b) (2\sqrt{6}+\sqrt{5})(2\sqrt{6}-5)
    =2\sqrt{6}.2\sqrt{6}-10\sqrt{6}+2\sqrt{30}-5\sqrt{5}
    =24-10\sqrt{6}+2\sqrt{30}-5\sqrt{5}
    c) (\sqrt{20}-3\sqrt{10}+\sqrt{5})\sqrt{5}+15\sqrt{2}
    =\sqrt{100}-3\sqrt{50}+\sqrt{5}.\sqrt{5}+15\sqrt{2}
    =10-15\sqrt{2}+5+15\sqrt{2}
    =15
     

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

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