so sánh các số sau a) $\sqrt[]{15}$ -1 và $\sqrt[]{10}$ b) $\sqrt[]{17}$ +3 và 4$\sqrt[]{3}$ c)-4 $\sqrt[]{5}$ +3 và – $\sqrt[]{37}$ d)- $\sqrt[

a)$\sqrt{15}<4\Rightarrow \sqrt{15}-1<3$

$\sqrt{10}>3$

$\Rightarrow \sqrt{15}-1<\sqrt{10}$

b)$\sqrt{17}>4\Rightarrow \sqrt{17}+3>7$

$4\sqrt{3}=\sqrt{48}<7$

$\Rightarrow \sqrt{17}+3>4\sqrt{3}$

c)$-4\sqrt{5}=-\sqrt{80}>-9\Rightarrow -4\sqrt{5}+3>-6$

$-\sqrt{37}<-6$

$\Rightarrow -4\sqrt{5}+3>-\sqrt{37}$

d)$-\sqrt{37}<-6\Rightarrow -\sqrt{37}-5<-11$

$-\sqrt{120}>-11$

$\Rightarrow -\sqrt{37}-5<-\sqrt{120}$

e)$1<\sqrt{2}<2\ ;\ 3<\sqrt{11}<4\\\Rightarrow 4<\sqrt{2}+\sqrt{11}<6$

$1<\sqrt{3}<2\Rightarrow 6<\sqrt{3}+5<7$

$\Rightarrow \sqrt{2}+\sqrt{11}<\sqrt{3}+5$