a) nhân ra thôi b

\(=\frac{\left(2\sqrt{10}-5\right)\left(9+\sqrt{10}\right)}{71}=\frac{18\sqrt{10}-45+20-5\sqrt{10}}{71}=\frac{-25+13\sqrt{10}}{71}.\)

b)cách khác nhé !\(\frac{9-2\sqrt{3}}{3\sqrt{6}-2\sqrt{2}}=\frac{\sqrt{3}\left(3\sqrt{3}-2\right)}{\sqrt{2}\left(3\sqrt{3}-2\right)}=\frac{\sqrt{3}}{\sqrt{2}}=\frac{\sqrt{6}}{2}.\)

Ta có : \(\sqrt{17}>\sqrt{16}\) , \(\sqrt{26}>\sqrt{25}\) 

=>\(\sqrt{17}+\sqrt{26}+1>\sqrt{16}+\sqrt{25}+1=4+5+1=10\)

mà \(\sqrt{99}< \sqrt{100}=10\) 

=> a > b

mình trình bày trong hình, hơi mờ bạn thông cảm!

như này là xịn lém rrr. Thănkiu nhìu nhó Nguyen Thu Hong

Lời giải:
ĐKXĐ: $x\leq 3$

PT $\Leftrightarrow \sqrt{15-x}=6-\sqrt{3-x}$

$\Rightarrow 15-x=36+3-x-12\sqrt{3-x}$ (bp hai vế)

$\Leftrightarrow 24=12\sqrt{3-x}$

$\Leftrightarrow 2=\sqrt{3-x}$

$\Rightarrow 3-x=4$

$\Leftrightarrow x=-1$ (thỏa mãn)

Thử lại thấy ok nên $x=-1$ là nghiệm duy nhất của pt.

y : 15 - 34,87 = 52,21 + 6

y : 15 - 34,87 = 58,21

Y : 15 = 58,21 +  34,87

Y : 15 = 93,08

Y =  93,08 x 15 

Y = 1396,2

nha bạn 

\(y:15-34,87=52,21+6\)

\(y:15-34,87=58,21\)

\(y:15=58,21+34,87\)

\(y:15=93,08\)

\(y=15\times93,08\)

\(y=1396,2\)

y: 15- 34,87= 52,21+ 6

y : 15- 34,87 = 58,21

y : 15            = 58,21+ 34,87

y : 15            = 93,08

y              = 93,08x 15

y              = 1396,2

\(\sqrt{\left(5+2\sqrt{6}\right).\left(5-2\sqrt{6}\right)}\\ =\sqrt{5^2-\left(2\sqrt{6}\right)^2}\\ =\sqrt{25-24}\\ =\sqrt{1}=1\)

\(\sqrt{5+2\sqrt{6}}\cdot\sqrt{5-2\sqrt{6}}\)

\(=\left(\sqrt{3}+\sqrt{2}\right)\left(\sqrt{3}-\sqrt{2}\right)\)

=1

a)\(\frac{3\sqrt{6}-\sqrt{2}}{1-3\sqrt{3}}=\frac{3\sqrt{3}.\sqrt{2}-\sqrt{2}}{1-3\sqrt{3}}=\frac{\sqrt{2}.\left(3\sqrt{3}-1\right)}{-\left(3\sqrt{3}-1\right)}=-\sqrt{2}\)

b)\(\frac{\sqrt{10}-\sqrt{15}}{\sqrt{8}-\sqrt{12}}=\frac{\sqrt{2}.\sqrt{5}-\sqrt{3}.\sqrt{5}}{2\sqrt{2}-2\sqrt{3}}=\frac{\sqrt{5}.\left(\sqrt{2}-\sqrt{3}\right)}{2.\left(\sqrt{2}-\sqrt{3}\right)}=\frac{\sqrt{5}}{2}\)

c)\(\frac{\sqrt{15}-\sqrt{6}}{\sqrt{35}-\sqrt{14}}=\frac{\sqrt{3}.\sqrt{5}-\sqrt{3}.\sqrt{2}}{\sqrt{5}.\sqrt{7}-\sqrt{7}.\sqrt{2}}=\frac{\sqrt{3}.\left(\sqrt{5}-\sqrt{2}\right)}{\sqrt{7}.\left(\sqrt{5}-\sqrt{2}\right)}=\frac{\sqrt{3}}{\sqrt{7}}\)

d)\(\frac{5\sqrt{6}-6\sqrt{5}}{\sqrt{5}-\sqrt{6}}=\frac{\sqrt{5^2.6}-\sqrt{6^2.5}}{\sqrt{5}-\sqrt{6}}=\frac{\sqrt{30}.\sqrt{5}-\sqrt{30}.\sqrt{6}}{\sqrt{5}-\sqrt{6}}=\frac{\sqrt{30}.\left(\sqrt{5}-\sqrt{6}\right)}{\sqrt{5}-\sqrt{6}}=\sqrt{30}\)

e)\(\frac{2\sqrt{3}-3\sqrt{2}}{\sqrt{6}}=\frac{\sqrt{2^2.3}-\sqrt{3^2.2}}{\sqrt{6}}=\frac{\sqrt{6}.\sqrt{2}-\sqrt{6}.\sqrt{3}}{\sqrt{6}}=\frac{\sqrt{6}.\left(\sqrt{2}-\sqrt{3}\right)}{\sqrt{6}}=\sqrt{2}-\sqrt{3}\)

f)\(\frac{6\sqrt{2}-4}{\sqrt{2}}=\frac{6\sqrt{2}-\sqrt{16}}{\sqrt{2}}=\frac{6\sqrt{2}-\sqrt{2}.2\sqrt{2}}{\sqrt{2}}=\frac{\sqrt{2}.\left(6-2\sqrt{2}\right)}{\sqrt{2}}=6-2\sqrt{2}\)

g)\(\frac{6-5\sqrt{3}}{\sqrt{3}}=\frac{\sqrt{36}-5\sqrt{3}}{\sqrt{3}}=\frac{\sqrt{3}.2\sqrt{3}-5\sqrt{3}}{\sqrt{3}}=\frac{\sqrt{3}.\left(2\sqrt{3}-5\right)}{\sqrt{3}}=2\sqrt{3}-5\)

Cảm ơn bạn nha

= 637364

637364