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

Toán Lớp 9: 1, phân tích thành tích: căn 15- căn 3 ; a căn b – b căn a; a+2 căn a +1

Toán Lớp 9: 1, phân tích thành tích: căn 15- căn 3 ; a căn b – b căn a; a+2 căn a +1

Comments ( 2 )

  1. \qquad \sqrt{15}-\sqrt{3}
    =\sqrt{3}.\sqrt{5}-\sqrt{3}
    =\sqrt{3}(\sqrt{5}-1)
    —————————–
    \qquad a\sqrt{b}-b\sqrt{a} ĐK: a>=0;b>=0
    =\sqrt{a}.\sqrt{ab}-\sqrt{b}.\sqrt{ab}
    =\sqrt{ab}(\sqrt{a}-\sqrt{b})
    —————————–
    \qquad a+2\sqrt{a}+1 ĐK: a>=0
    =(\sqrt{a}+1)^2
     

  2. ~rai~
    \(a)\sqrt{15}-\sqrt{3}\\=\sqrt{3}.\sqrt{5}-\sqrt{3}\\=\sqrt{3}.(\sqrt{5}-1).\\b)a\sqrt{b}-b\sqrt{a}\\=\sqrt{ab}.\sqrt{a}-\sqrt{ab}.\sqrt{b}\\=\sqrt{ab}.(\sqrt{a}-\sqrt{b}).\\c)a+2\sqrt{a}+1\\=(\sqrt{a})^2+2\sqrt{a}.1+1^2\\=(\sqrt{a}+1)^2.\\\text{Áp dụng hàng đẳng thức:}A^2+2AB+B^2=(A+B)^2.\)

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