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

Toán Lớp 8: So sánh: a) $\sqrt{31}$ – $\sqrt{19}$ và 6 – $\sqrt{17}$ b) 9 – $\sqrt{58}$ và $\sqrt{80}$ – $\sqrt{59}$

Toán Lớp 8: So sánh:
a) $\sqrt{31}$ – $\sqrt{19}$ và 6 – $\sqrt{17}$
b) 9 – $\sqrt{58}$ và $\sqrt{80}$ – $\sqrt{59}$

Comments ( 1 )

  1. a,
    Ta có:
    $0<31<36$
    $\to \sqrt{31}<\sqrt{36}$
    $\to \sqrt{31}<6$                  $(1)$
    $19>17>0$
    $\to \sqrt{19}>\sqrt{17}$
    $\to -\sqrt{19}<-\sqrt{17}$   $(2)$
    $(1)+(2)\to \sqrt{31}-\sqrt{19}<6-\sqrt{17}$
    b,
    Ta có:
    $0<80<81$
    $\to \sqrt{80}<\sqrt{81}$
    $\to 9>\sqrt{80}$                  $(1)$
    $0<58<59$
    $\to \sqrt{58}<\sqrt{59}$
    $\to -\sqrt{58}>-\sqrt{59}$   $(2)$
    $(1)+(2)\to 9-\sqrt{58}>\sqrt{80}-\sqrt{59}$

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

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