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b: \(5+2\sqrt{6}=\left(\sqrt{3}+\sqrt{2}\right)^2\)

c: \(13+\sqrt{48}=13+4\sqrt{3}=\left(2\sqrt{3}+1\right)^2\)

d: \(4+2\sqrt{3}=\left(\sqrt{3}+1\right)^2\)

14 tháng 5 2018

1/ \(7-2\sqrt{6}=\left(\sqrt{6}\right)^2-2\sqrt{6}+1\)

\(=\left(\sqrt{6}-1\right)^2\)

2/ \(10+2\sqrt{21}=\left(\sqrt{7}\right)^2+2.\sqrt{7}.\sqrt{3}+\left(\sqrt{3}\right)^2\)

\(=\left(\sqrt{7}+\sqrt{3}\right)^2\)

4/ \(10+4\sqrt{6}=2^2+2.2.\sqrt{6}+\left(\sqrt{6}\right)^2\)

\(=\left(2+\sqrt{6}\right)^2\)

5/ \(11-2\sqrt{30}=\left(\sqrt{6}\right)^2-2.\sqrt{6}.\sqrt{5}+\left(\sqrt{5}\right)^2\)

= \(\left(\sqrt{6}-\sqrt{5}\right)^2\)

8/ \(11+4\sqrt{7}=2^2+2.2.\sqrt{7}+\left(\sqrt{7}\right)^2\)

= \(\left(2+\sqrt{7}\right)^2\)

10/ \(12+6\sqrt{3}=3^2+2.3.\sqrt{3}+\left(\sqrt{3}\right)^2\)

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

NV
1 tháng 8 2021

\(\sqrt{7+4\sqrt{3}}=\sqrt{\left(2+\sqrt{3}\right)^2}=2+\sqrt{3}\)

\(\sqrt{8-2\sqrt{12}}=\sqrt{\left(\sqrt{6}-\sqrt{2}\right)^2}=\left|\sqrt{6}-\sqrt{2}\right|=\sqrt{6}-\sqrt{2}\)

\(\sqrt{21+6\sqrt{6}}=\sqrt{\left(3\sqrt{2}-\sqrt{3}\right)^2}=\left|3\sqrt{2}-\sqrt{3}\right|=3\sqrt{2}-\sqrt{3}\)

\(\sqrt{15-6\sqrt{6}}=\sqrt{\left(3-\sqrt{6}\right)^2}=\left|3-\sqrt{6}\right|=3-\sqrt{6}\)

\(\sqrt{29-12\sqrt{5}}=\sqrt{\left(2\sqrt{5}-3\right)^2}=\left|2\sqrt{5}-3\right|=2\sqrt{5}-3\)

\(\sqrt{41+12\sqrt{5}}=\sqrt{\left(6+\sqrt{5}\right)^2}=6+\sqrt{5}\)

13 tháng 6 2015

a,\(5+\sqrt{24}=5+\sqrt{6.4}=5+2\sqrt{6}=\left(\sqrt{2}\right)^2+2\sqrt{2}\sqrt{3}+\left(\sqrt{3}\right)^2=\left(\sqrt{2}+\sqrt{3}\right)^2\)

b,\(14+6\sqrt{5}=14+2.3.\sqrt{5}=3^2+2.3\sqrt{5}+\left(\sqrt{5}\right)^2=\left(3+\sqrt{5}\right)^2\)

13 tháng 6 2015

Ấn đúng cho mình nha ( hãy kết bạn với tui)

12 tháng 6 2018

1)\(43-30\sqrt{2}=\left(5-3\sqrt{2}\right)^2\)

2)\(21+4\sqrt{5}=\left(1+2\sqrt{5}\right)^2\)

13 tháng 6 2018

1/ \(5^2-2\cdot5\cdot3\sqrt{2}+\left(3\sqrt{2}\right)^2=\left(5-3\sqrt{2}\right)^2\)

2/\(1^2+2\cdot2\sqrt{5}+\left(2\sqrt{5}\right)^2=\left(1+2\sqrt{5}\right)^2\)

22 tháng 11 2020

MK KO BT MK MỚI HO C LỚP 6

AI HỌC LỚP 6 CHO MK XIN

3 tháng 9 2016

1) \(15-\sqrt{216}=15-\sqrt{4}.\sqrt{54}\)=\(9-2.\sqrt{9}.\sqrt{6}+6\)=\(\left(\sqrt{9}-\sqrt{6}\right)^2=\left(3-\sqrt{6}\right)^2\)

2)\(20-\sqrt{76}=20-\sqrt{4}.\sqrt{19}=19-2\sqrt{19}.1+1=\left(\sqrt{19}-1\right)^2\)

3)\(24-12\sqrt{3}=6\left(4-2\sqrt{3}\right)=6\left(3-2.\sqrt{3}.1+1\right)=6\left(\sqrt{3}-1\right)^2\)

4)\(7-\sqrt{13}=\frac{14-2\sqrt{13}}{2}=\frac{13-2\sqrt{13}.1+1}{2}=\frac{\left(\sqrt{13}-1\right)^2}{2}\)

5)\(16-\sqrt{31}=\frac{32-2\sqrt{31}}{2}=\frac{31-2\sqrt{31}.1+1}{2}=\frac{\left(\sqrt{31}-1\right)^2}{2}\)

31 tháng 8 2017

1) \(5-2\sqrt{6}=\left(\sqrt{3}\right)^2-2\sqrt{3}.\sqrt{2}+\left(\sqrt{2}\right)^2=\left(\sqrt{3}-\sqrt{2}\right)^2\)

2) \(8+2\sqrt{15}=\left(\sqrt{5}\right)^2+2\sqrt{5}.\sqrt{3}+\left(\sqrt{3}\right)^2=\left(\sqrt{5}+\sqrt{3}\right)^2\)

3) \(10-2\sqrt{21}=\left(\sqrt{7}\right)^2-2\sqrt{7}.\sqrt{3}+\left(\sqrt{3}\right)^2=\left(\sqrt{7}-\sqrt{3}\right)^2\)

4) \(21+6\sqrt{6}=\left(\sqrt{18}\right)^2+2.\sqrt{18}.\sqrt{3}+\left(\sqrt{3}\right)^2=\left(\sqrt{18}+\sqrt{3}\right)^2\)

5) \(14+8\sqrt{3}=\left(\sqrt{8}\right)^2+2.\sqrt{8}.\sqrt{6}+\left(\sqrt{6}\right)^2=\left(\sqrt{8}+\sqrt{6}\right)^2\)

6) \(36-12\sqrt{5}=\left(\sqrt{30}\right)^2-2.\sqrt{30}.\sqrt{6}+\left(\sqrt{6}\right)^2=\left(\sqrt{30}-\sqrt{6}\right)^2\)

7) \(25+4\sqrt{6}=\left(\sqrt{24}\right)^2+2\sqrt{24}.1+1^2=\left(\sqrt{24}+1\right)^2\)

8) \(98-16\sqrt{3}=\left(\sqrt{96}\right)^2-2\sqrt{96}.\sqrt{2}+\left(\sqrt{2}\right)^2=\left(\sqrt{96}-\sqrt{2}\right)^2\)

2 tháng 9 2017

\(13-4\sqrt{3}=\left(2\sqrt{3}\right)^2-2.2\sqrt{2}.1+1^2=\left(2\sqrt{3}-1\right)^2\)

a) \(\left(\sqrt{5}+\sqrt{3}\right)\sqrt{8-2\sqrt{15}}=\left(\sqrt{5}+\sqrt{3}\right)\left(\sqrt{5}-\sqrt{3}\right)=5-3=2\)

câu này \(\sqrt{15}\)đúng hơn \(\sqrt{5}\)

b) \(\sqrt{3-\sqrt{5}}-\sqrt{3+\sqrt{5}}=\frac{\sqrt{6-2\sqrt{5}}-\sqrt{6+2\sqrt{5}}}{\sqrt{2}}=\frac{\sqrt{5}-1-\sqrt{5}-1}{\sqrt{2}}=\frac{-2}{\sqrt{2}}=-\sqrt{2}\)c) \(\sqrt{5-2\sqrt{6}}-\sqrt{5+2\sqrt{6}}=\sqrt{3}-\sqrt{2}-\sqrt{3}-\sqrt{2}=-2\sqrt{2}\)