\(\sqrt{81.16.169}=\sqrt{81}.\sqrt{16}.\sqrt{169}=9.4.13=468\)

\(\sqrt{10}.\sqrt{810}=\sqrt{10.10}.\sqrt{81}=10.9=90\)

\(\sqrt{64}.\sqrt{81.100}-\sqrt{64}.\sqrt{196.16}=\sqrt{64}\left(\sqrt{81}.\sqrt{100}-\sqrt{196}.\sqrt{16}\right)=8.\left(9.10-14.4\right)=8.34=272\)

a: \(\sqrt{81\cdot16\cdot169}=\sqrt{81}\cdot\sqrt{16}\cdot\sqrt{169}\)

\(=9\cdot4\cdot13\)

\(=36\cdot13=468\)

b: \(\sqrt{10}\cdot\sqrt{810}=\sqrt{810\cdot10}\)

\(=\sqrt{81\cdot100}=9\cdot10=90\)

c: \(\sqrt{64}\cdot\sqrt{81\cdot100}-\sqrt{64}\cdot\sqrt{196\cdot16}\)

\(=\sqrt{64}\cdot\sqrt{81}\cdot\sqrt{100}-\sqrt{64}\cdot\sqrt{196}\cdot\sqrt{16}\)

\(=8\cdot9\cdot10-8\cdot14\cdot4\)

=720-448

=272

a) \(\sqrt{16}.\sqrt{25}+\sqrt{196}:\sqrt{49}\)

=4.5+14:7

=20+2

=22

b) chưa học nhó:))

Cảm ơn bạn nhỏ :))

a) \(\sqrt{16}\cdot\sqrt{25}+\sqrt{196}:\sqrt{49}\)

\(=\sqrt{16\cdot25}+\sqrt{196:49}\)

\(=20+2=22\)

b) \(36:\sqrt{2\cdot3^2\cdot18}-\sqrt{169}\)

\(=36:\sqrt{324}-\sqrt{169}\)

\(=36:18-13=2-13=-11\)

c) \(\sqrt{\sqrt{81}}\)

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

d) \(\sqrt{3^2+4^2}\)

\(=\sqrt{9+16}=\sqrt{25}=5\)

a) \(\sqrt{16}.\sqrt{25}+\sqrt{196}\div\sqrt{49}\)

\(=4.5+14:7\)

\(=20+2=22\)

b) \(36:\sqrt{2.3^2.18}-\sqrt{169}\)

\(=36:18-13=-11\)

c) \(\sqrt{\sqrt{81}}=\sqrt{9}=3\)

d) \(\sqrt{3^2+4^2}=\sqrt{25}=5\)

a) \(\sqrt{16}+\sqrt{1}-3\sqrt{9}=4+1-3.3=-4\)

b) \(\sqrt{\dfrac{4}{9}}-\sqrt{25}+\sqrt{100}=\dfrac{2}{3}-5+10=\dfrac{17}{3}\)

c) \(2\sqrt{169}+3\sqrt{196}-2\sqrt{289}\)

= \(2.13+3.14-2.17=34\)

\(=20+\frac{14}{7}=20+2=22\)

a) \(\sqrt{\frac{196}{169}}=\frac{14}{13}\)

b) \(\sqrt{2\frac{14}{25}}=\sqrt{\frac{64}{25}}=\frac{8}{5}\)

c) \(\sqrt{\frac{0,36}{25}}=\frac{0,6}{5}=\frac{3}{25}\)

d) \(\sqrt{\frac{6,4}{4,9}}=\sqrt{\frac{64}{49}}=\frac{8}{7}\)

a) \(\sqrt{\frac{196}{169}}=\sqrt{\left(\frac{14}{13}\right)^2}=\frac{14}{13}\)

b) \(\sqrt{2\frac{14}{25}}=\sqrt{\frac{64}{25}}=\sqrt{\left(\frac{8}{5}\right)^2}=\frac{8}{5}\)

c) \(\sqrt{\frac{0,36}{25}}=\sqrt{\left(\frac{0,6}{5}\right)^2}=\frac{0,6}{5}=\frac{6}{50}=\frac{3}{25}\)

d) \(\sqrt{\frac{6,4}{4,9}}=\sqrt{\frac{64}{49}}=\sqrt{\left(\frac{8}{7}\right)^2}=\frac{8}{7}\)

Bài 2:

a) Ta có: \(\sqrt{4}+\sqrt{25}+\sqrt{64}+...+\sqrt{2500}\)

\(=2+5+8+...+50\)

Số hạng tử là: \(\frac{50-2}{3}+1=\frac{48}{3}+1=16+1=17\)(số)

Tổng của dãy số là: \(\left(50+2\right)\cdot\frac{17}{2}=\frac{52\cdot17}{2}=26\cdot17=442\)

b) Ta có: \(\sqrt{1}+\sqrt{25}+\sqrt{81}+...+\sqrt{9409}\)

\(=1+5+9+...+97\)

Số hạng tử là:

\(\frac{97-1}{4}+1=\frac{96}{4}+1=24+1=25\)(số)

Tổng của dãy số là: \(\left(97+1\right)\cdot\frac{25}{2}=\frac{98\cdot25}{2}=49\cdot25=1225\)

Đáp án của câu a là 3, còn đáp án của câu b là 22

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câu b) của bạn nhé

= 4.5 + 14:7 = 20 + 2 = 22