a)\(\sqrt{10}\cdot\sqrt{40}=\sqrt{10\cdot40}=\sqrt{400}=20\)

b) \(\sqrt{2}\cdot\sqrt{162}=\sqrt{2\cdot162}=\sqrt{2\cdot2\cdot81}=\sqrt{4}\cdot\sqrt{81}=2\cdot9=18\)

a) \(\sqrt{10}.\sqrt{40}\)

=\(\sqrt{10.40}\)

=\(\sqrt{400}\)

=20

b) \(\sqrt{5.}\sqrt{45}\)

=\(\sqrt{5.45}\)

=\(\sqrt{225}\)

=\(\sqrt{15}\)

c) \(\sqrt{52.}\sqrt{13}\)

=\(\sqrt{52.13}\)

=\(\sqrt{676}\)

=26

d)\(\sqrt{2.}\sqrt{162}\)

=\(\sqrt{2.162}\)

=\(\sqrt{324}\)

=18

b)

=15

a) \(\sqrt{10}.\sqrt{40}=\sqrt{10.40}=\sqrt{400}=20\)

b) \(\sqrt{5}.\sqrt{45}=\sqrt{5.45}=\sqrt{225}=15\)

c) \(\sqrt{52}.\sqrt{13}=\sqrt{52.13}=\sqrt{676}=26\)

d) \(\sqrt{2}.\sqrt{162}=\sqrt{2.162}=\sqrt{324}=18\)

Áp dụng quy tắc chia hai căn bậc hai, hãy tính :

230023" id="MathJax-Element-1-Frame" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" tabindex="0">2300−−−−√23−−√ = \(\sqrt{\dfrac{2300}{23}}\) = \(\sqrt{100}\) = 10

12,50,5" id="MathJax-Element-2-Frame" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" tabindex="0">12,5−−−−√0,5−−−√ = \(\sqrt{\dfrac{12,5}{0,5}}\) = \(\sqrt{25}\) = 5

19212" id="MathJax-Element-3-Frame" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" tabindex="0">192−−−√12−−√ = \(\sqrt{\dfrac{192}{12}}\) = \(\sqrt{16}\) = 4

6150" id="MathJax-Element-4-Frame" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-table; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" tabindex="0">6–√150−−−√ = \(\sqrt{\dfrac{6}{150}}\) = \(\sqrt{\dfrac{1}{25}}\) = \(\dfrac{1}{5}\)

a) = \(\sqrt{10.40}=\sqrt{400}=\sqrt{20^2}=20\)

b) \(=\sqrt{5.45}=\sqrt{5^2.3^2}=\sqrt{15^2}=15\)

a) \(\sqrt{0,4}.\sqrt{6,4}=\sqrt{0,4.6,4}=\sqrt{\frac{4}{10}.\frac{64}{10}}=\sqrt{\frac{\left(2.8\right)^2}{10^2}}=\frac{16}{10}=\frac{8}{5}\)

b) \(\sqrt{2,7}.\sqrt{5}.\sqrt{1,5}=\sqrt{\frac{27}{10}.5.\frac{15}{10}}=\sqrt{\frac{3^3.5^2.3}{10^2}}=\sqrt{\frac{\left(3^2.5\right)^2}{10^2}}=\frac{45}{10}=\frac{9}{2}\)

câu này dễ mà

chỉ cần nhân vào là xong

kiến thức đầu lớp 9 khá dễ đấy

tự mình làm đi nha bạn

Ta thấy các số trong căn bậc hai đều lớn hơn 0, áp dụng \(\sqrt{a\cdot b}=\sqrt{a}\cdot\sqrt{b}\)

a) \(\sqrt{7}\cdot\sqrt{63}=\sqrt{7\cdot63}=21\)

b) \(\sqrt{2,5}\cdot\sqrt{30}\cdot\sqrt{48}=\sqrt{2,5\cdot30\cdot48}=60\)

c) \(\sqrt{0,4}\cdot\sqrt{6,4}=\sqrt{0,4\cdot6,4}=1,6\)

d) \(\sqrt{2,7}\cdot\sqrt{5}\cdot\sqrt{1,5}=\sqrt{2,7\cdot5\cdot1,5}=4,5\)

a. \(\sqrt{7}.\sqrt{63}=\sqrt{7.63}=\sqrt{441}=21\)

b.\(\sqrt{2,5}.\sqrt{30}.\sqrt{48}=\sqrt{2,5.30.48}=\sqrt{3600}=60\)

c.\(\sqrt{0,4}.\sqrt{6,4}=\sqrt{0,4.6,4}=\sqrt{2,56}=1,6\)

d.\(\sqrt{2,7}.\sqrt{5}.\sqrt{1,5}=\sqrt{2,7.5.1,5}=\sqrt{20,25}=4,5\)

\(\sqrt{7}.\sqrt{63}=\sqrt{7.63}=\sqrt{441}=21\)

\(\sqrt{2,5}.\sqrt{30}.\sqrt{48}=\sqrt{2,5.30.48}=\sqrt{3600}=60\)

\(\sqrt{0,4}.\sqrt{6,4}=\sqrt{0,4.6,4}=\sqrt{2,56}=1,6\)

\(\sqrt{2,7}.\sqrt{5}.\sqrt{1,5}=\sqrt{2,7.5.1,5}=\sqrt{20,25}=4,5\)

Học tốt nhé :)

a)\(\sqrt{7.63}\)=21

b)\(\sqrt{2,5.30.48}\)=60

c)\(\sqrt{0,4.6,4}\)=1,6

d)\(\sqrt{2,7.5.1,5}\)=4,5

a) $\sqrt{7}.\sqrt{63}=\sqrt{7.63}=\sqrt{{\mathrm{7.7.3}}^2}=\sqrt{(7.3{)}^2}=7.3=21$.

b) $\sqrt{2,5}.\sqrt{30}.\sqrt{48}=\sqrt{2,\mathrm{5.30.48}}=\sqrt{\mathrm{25.3.48}}$

$\sqrt{5^2.3.3{.4}^2}=\sqrt{(\mathrm{5.3.4}{)}^2}=\mathrm{5.3.4}=60$.

c) $\sqrt{0,4}.\sqrt{6,4}=\sqrt{0,4.6,4}=\sqrt{0,04.64}$

$=\sqrt{0,2^2{.8}^2}=\sqrt{(0,2.8{)}^2}=0,2.8=1,6$.

d) $\sqrt{2,7}.\sqrt{5}.\sqrt{1,5}=\sqrt{2,\mathrm{7.5.1},5}$

$=\sqrt{3^2.0,\mathrm{3.5.5.0},3}=\sqrt{(3.0,3.5{)}^2}=4,5$.

Áp dụng quy tắc khai phương một tích

1: Ta có: \(\sqrt{\frac{1}{5}}\cdot\sqrt{\frac{1}{20}}\cdot3\cdot7\)

\(=\sqrt{\frac{1}{5}}\cdot\sqrt{\frac{1}{20}}\cdot\sqrt{9}\cdot\sqrt{49}\)

\(=\sqrt{\frac{1}{5}\cdot\frac{1}{20}\cdot9\cdot49}\)

\(=\sqrt{\frac{441}{100}}=\frac{\sqrt{441}}{\sqrt{100}}=\frac{21}{10}\)

2: Ta có: \(\sqrt{0,001\cdot360\cdot3^2\cdot\left(-3\right)^2}\)

\(=\sqrt{0,001}\cdot\sqrt{360}\cdot\sqrt{3^{^2}}\cdot\sqrt{\left(-3\right)^2}\)

\(=\sqrt{\frac{1}{100}}\cdot\sqrt{\frac{1}{10}}\cdot\sqrt{6^2}\cdot\sqrt{10}\cdot3\cdot3\)

\(=\frac{1}{10}\cdot6\cdot9\cdot\sqrt{\frac{1}{10}\cdot10}=\frac{54}{10}\cdot1=\frac{27}{5}\)

Áp dụng quy tắc nhân căn thức bậc hai

1: Ta có: \(2\sqrt{2}\left(4\sqrt{8}-\sqrt{32}\right)\)

\(=2\sqrt{2}\cdot4\sqrt{8}-2\sqrt{2}\cdot\sqrt{32}\)

\(=8\cdot\sqrt{16}-2\cdot\sqrt{64}\)

\(=8\cdot4-2\cdot8\)

=32-16=16

2300 23 = 2300 23 = 100 = 10