13244

13244 sai roi do

a,\(\left(5+4\sqrt{2}\right)\left(3+2\sqrt{1+\sqrt{2}}\right)\left(3-2\sqrt{1+\sqrt{2}}\right)\)

=\(\left(5+4\sqrt{2}\right)\left(9-4\left(1+\sqrt{2}\right)\right)\)

=\(\left(5+4\sqrt{2}\right)\left(9-4-4\sqrt{2}\right)\)

=\(\left(5+4\sqrt{2}\right)\left(5-4\sqrt{2}\right)=25-\left(4\sqrt{2}\right)^2\)

=-7

b, \(\sqrt{\frac{9}{4}-\sqrt{2}}=\sqrt{\frac{9-4\sqrt{2}}{4}}=\frac{\sqrt{9-4\sqrt{2}}}{2}=\frac{\sqrt{9-2\sqrt{8}}}{2}=\frac{\sqrt{\left(\sqrt{8}-1\right)^2}}{2}=\frac{\left|\sqrt{8}-1\right|}{2}=\frac{\sqrt{8}-1}{2}\)

So sánh:

1) \(2\sqrt{27}\) và \(\sqrt{147}\)

+ \(2\sqrt{27}\) = \(6\sqrt{3}\)

+ \(\sqrt{147}\) = \(7\sqrt{3}\)

⇒ \(6\sqrt{3}\) < \(7\sqrt{3}\)

Vậy: \(2\sqrt{27}\)< \(\sqrt{147}\)

2) \(2\sqrt{15}\) và \(\sqrt{59}\)

+ \(2\sqrt{15}\) = \(\sqrt{60}\)

⇒ \(\sqrt{60}\) > \(\sqrt{59}\)

Vậy: \(2\sqrt{15}\) > \(\sqrt{59}\)

3) \(2\sqrt{2}-1\) và 2

\(giống\left(-1\right)\left\{{}\begin{matrix}3-1\\2\sqrt{2}-1\end{matrix}\right.\)

So sánh: 3 và \(2\sqrt{2}\)

+ 3 = \(\sqrt{9}\)

+ \(2\sqrt{2}=\sqrt{8}\)

⇒ \(\sqrt{8}\) < \(\sqrt{9}\)

⇒ \(\sqrt{8}\) -1 < \(\sqrt{9}\) -1

⇒ \(2\sqrt{2}\) - 1 < 3 - 1

Vậy: \(2\sqrt{2}-1< 2\)

4) \(\frac{\sqrt{3}}{2}\) và 1

+ 1 = \(\frac{2}{2}\)

⇒ \(\frac{\sqrt{3}}{2}\) < \(\frac{2}{2}\)

Vậy: \(\frac{\sqrt{3}}{2}\) < 1

5) \(\frac{-\sqrt{10}}{2}\) và \(-2\sqrt{5}\)

+ \(-2\sqrt{5}\) = \(\frac{-4\sqrt{5}}{2}\) = \(\frac{-\sqrt{80}}{2}\)

⇒ \(\frac{-\sqrt{10}}{2}\) > \(\frac{-\sqrt{80}}{2}\)

Vậy: \(\frac{-\sqrt{10}}{2}\) > \(-2\sqrt{5}\)

cho mình hỏi "va"là gì zợ

và

7/10=0.7 ; 7/100=0.07 ; 6 và 38/100=6.38 ; 2014/100=2.014 ; 3/2=1.5 ; 2/5=0.4 ; 1 và 1/4=1.25

5/8 sửa nhé

SAO CHUA CO AI TRA LOI VAY =}}

  1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7+1/7x1/8+1/8x1/9

=7/18