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

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

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) $\sqrt{2,7}$

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

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−−−√ = \(\sqrt{\dfrac{6}{150}}\) = \(\sqrt{\dfrac{1}{25}}\) = \(\dfrac{1}{5}\)

\(a.\sqrt{0,4}.\sqrt{64}=\sqrt{0,4.64}=\sqrt{25,6}\)

\(b.\sqrt{5,2}.\sqrt{1,3}=\sqrt{5,2.1,3}=\sqrt{6,76}=2.6\)

\(c.\sqrt{12,1}.\sqrt{360}=\sqrt{12,1.360}=\sqrt{4356}=66\)