\(\left(2\sqrt{5}-\sqrt{3}\right)\left(23+2\sqrt{15}\right)-\left(2\sqrt{5}+\sqrt{3}\right)\left(23-2\sqrt{15}\right)\)= ?
Những câu hỏi liên quan
Tính
a/ \(\sqrt{2-\sqrt{3}}-\sqrt{6+3\sqrt{3}}\)
b/ \(\left(2\sqrt{5}-\sqrt{3}\right)\left(23+2\sqrt{15}\right)-\left(2\sqrt{5}+\sqrt{3}\right)\left(23-2\sqrt{15}\right)\)
Thực hiện phép tính:
Aleft(sqrt{2}+sqrt{3}+sqrt{5}right).left(sqrt{2}+sqrt{3}-sqrt{5}right).left(sqrt{2}-sqrt{3}+sqrt{5}right).left(-sqrt{2}+sqrt{3}+sqrt{5}right)
Bsqrt{8-2sqrt{15}}-sqrt{23-4sqrt{5}}
Cleft(sqrt{3}-sqrt{2}right).sqrt{5-2sqrt{6}}
Dsqrt{13+30sqrt{2+sqrt{9+4sqrt{2}}}}
Đọc tiếp
Thực hiện phép tính:
A=\(\left(\sqrt{2}+\sqrt{3}+\sqrt{5}\right).\left(\sqrt{2}+\sqrt{3}-\sqrt{5}\right).\left(\sqrt{2}-\sqrt{3}+\sqrt{5}\right).\left(-\sqrt{2}+\sqrt{3}+\sqrt{5}\right)\)
B=\(\sqrt{8-2\sqrt{15}}-\sqrt{23-4\sqrt{5}}\)
C=\(\left(\sqrt{3}-\sqrt{2}\right).\sqrt{5-2\sqrt{6}}\)
D=\(\sqrt{13+30\sqrt{2+\sqrt{9+4\sqrt{2}}}}\)
Bạn nhóm hai thừa số đầu, hai thừa số cuối, sau đó áp dụng hằng đẳng thức số 3 ta dc
A=[(√2+√3)^2-5][5-(√2-√3)^2]
= Bạn khai triển các bình phương ra, thu gọn, kết quả là 24
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Bạn tách các bt trong ngoặc ra về các hằng đẳng thức số1, 2 như này
8-2√15= 3-2.√3.√5+5=
(√3+√5)^2.
Nhưng căn tiếp theo phải là 21-4√5 thì mới ra được là (2√5-1)^2
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Những câu tiếp theo hoàn toàn tương tự
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Thực hiện phép tính:
a) \(\left(\frac{1}{7-4\sqrt{3}}+\frac{3}{7+4\sqrt{3}}\right)\left(7+2\sqrt{3}\right)\)
b)\(\left(\frac{3\sqrt{5}-\sqrt{15}}{\sqrt{27}-3}+\frac{2\sqrt{5}}{\sqrt{3}}\right).4\sqrt{15}\)
c)\(\sqrt{5-2\sqrt{6-25-\sqrt{96}}}\)
d)\(\sqrt{23-2\sqrt{112}}+\sqrt{23+2\sqrt{112}}\)
a/ \(=\left(7+4\sqrt{3}+3\left(7-4\sqrt{3}\right)\right)\left(7+2\sqrt{3}\right)\)
\(=\left(28-8\sqrt{3}\right)\left(7+2\sqrt{3}\right)\)
\(=4\left(7-2\sqrt{3}\right)\left(7+2\sqrt{3}\right)\)
\(=4\left(49-12\right)=...\)
b/ \(=\left(\frac{\sqrt{15}\left(\sqrt{3}-1\right)}{3\left(\sqrt{3}-1\right)}+\frac{2\sqrt{15}}{3}\right).4\sqrt{15}\)
\(=\left(\frac{\sqrt{15}}{3}+\frac{2\sqrt{15}}{3}\right).4\sqrt{15}\)
\(=\sqrt{15}.4\sqrt{15}=4.15=...\)
c/ Bạn coi lại đề
d/ \(\sqrt{23-2\sqrt{112}}+\sqrt{23+2\sqrt{112}}\)
\(=\sqrt{\left(4-\sqrt{7}\right)^2}+\sqrt{\left(4+\sqrt{7}\right)^2}\)
\(=4-\sqrt{7}+4+\sqrt{7}=8\)
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tính1.left(sqrt{15}-2sqrt{3}right)^2+12sqrt{5}2.3sqrt{2}left(4-sqrt{2}right)+3left(1-2sqrt{2}right)^23.dfrac{1}{2}left(sqrt{6}+sqrt{5}right)^2-dfrac{1}{4}sqrt{120}-sqrt{dfrac{15}{2}}4.left(sqrt{4-sqrt{7}}-sqrt{4+sqrt{7}}right)^25.left(sqrt{sqrt{14}+sqrt{5}}+sqrt{sqrt{14}-sqrt{5}}right)^26.left(sqrt{3}+1right)^3-left(sqrt{3}-1right)^37.left(sqrt{2}+1right)^3-left(sqrt{2}-1right)^38.sqrt{13-sqrt{160}}-sqrt{53+4sqrt{90}}9.sqrt{3-sqrt{5}}+sqrt{3+sqrt{5}}
Đọc tiếp
tính
1.\(\left(\sqrt{15}-2\sqrt{3}\right)^2+12\sqrt{5}\)
2.\(3\sqrt{2}\left(4-\sqrt{2}\right)+3\left(1-2\sqrt{2}\right)^2\)
3.\(\dfrac{1}{2}\left(\sqrt{6}+\sqrt{5}\right)^2-\dfrac{1}{4}\sqrt{120}-\sqrt{\dfrac{15}{2}}\)
4.\(\left(\sqrt{4-\sqrt{7}}-\sqrt{4+\sqrt{7}}\right)^2\)
5.\(\left(\sqrt{\sqrt{14}+\sqrt{5}}+\sqrt{\sqrt{14}-\sqrt{5}}\right)^2\)
6.\(\left(\sqrt{3}+1\right)^3-\left(\sqrt{3}-1\right)^3\)
7.\(\left(\sqrt{2}+1\right)^3-\left(\sqrt{2}-1\right)^3\)
8.\(\sqrt{13-\sqrt{160}}-\sqrt{53+4\sqrt{90}}\)
9.\(\sqrt{3-\sqrt{5}}+\sqrt{3+\sqrt{5}}\)
Thu gọn B= \(21\left(\sqrt{2+\sqrt{3}}+\sqrt{3-\sqrt{5}}\right)^2-6\left(\sqrt{2-\sqrt{3}}+\sqrt{3+\sqrt{5}}\right)^2-15\sqrt{5}\)
Thu gọn A= \(\left(2-\sqrt{3}\right)\sqrt{26+15\sqrt{3}}-\left(2+\sqrt{3}\right)\sqrt{26-15\sqrt{3}}\)
Sửa đề
\(A=\left(2-\sqrt{3}\right)\sqrt[3]{26+15\sqrt{3}}-\left(2+\sqrt{3}\right)\sqrt[3]{26-15\sqrt{3}}\)
\(=\left(2-\sqrt{3}\right)\sqrt[3]{8+12\sqrt{3}+18+3\sqrt{3}}-\left(2+\sqrt{3}\right)\sqrt[3]{8-12\sqrt{3}+18-3\sqrt{3}}\)
\(=\left(2-\sqrt{3}\right)\sqrt[3]{\left(2+\sqrt{3}\right)^3}-\left(2+\sqrt{3}\right)\sqrt[3]{\left(2-\sqrt{3}\right)^3}\)
\(=\left(2-\sqrt{3}\right)\left(2+\sqrt{3}\right)-\left(2+\sqrt{3}\right)\left(2-\sqrt{3}\right)=0\)
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\(B=\left(2-\sqrt{3}\right).\sqrt{26+15\sqrt{3}}-\left(2+\sqrt{3}\right).\sqrt{26-15\sqrt{3}}\)
\(C=\left(\sqrt{10}-\sqrt{2}\right).\sqrt{3+\sqrt{5}}\)
Tính (rút gọn)
a) left(sqrt{3+sqrt{5}}right)left(sqrt{10}+sqrt{2}right)left(3-sqrt{5}right)
b) left(4+sqrt{15}right)left(sqrt{10-sqrt{6}}right)sqrt{4-}sqrt{15}
c) left(sqrt{6}+sqrt{2}right)left(sqrt{3}-2right)sqrt{sqrt{3+2}}
d) left(2sqrt{4+sqrt{6-2sqrt{5}}}right)left(sqrt{10}-sqrt{2}right)
f)sqrt{dfrac{3-sqrt{5}}{2-sqrt{3}}}
g)dfrac{sqrt{2+sqrt{3}}}{3+sqrt{3}}
h)sqrt{4-sqrt{15}}+sqrt{4+sqrt{15}}-2sqrt{3-sqrt{5}}
Đọc tiếp
Tính (rút gọn)
a) \(\left(\sqrt{3+\sqrt{5}}\right)\left(\sqrt{10}+\sqrt{2}\right)\left(3-\sqrt{5}\right)\)
b) \(\left(4+\sqrt{15}\right)\left(\sqrt{10-\sqrt{6}}\right)\sqrt{4-}\sqrt{15}\)
c) \(\left(\sqrt{6}+\sqrt{2}\right)\left(\sqrt{3}-2\right)\sqrt{\sqrt{3+2}}\)
d) \(\left(2\sqrt{4+\sqrt{6-2\sqrt{5}}}\right)\left(\sqrt{10}-\sqrt{2}\right)\)
f)\(\sqrt{\dfrac{3-\sqrt{5}}{2-\sqrt{3}}}\)
g)\(\dfrac{\sqrt{2+\sqrt{3}}}{3+\sqrt{3}}\)
h)\(\sqrt{4-\sqrt{15}}+\sqrt{4+\sqrt{15}}-2\sqrt{3-\sqrt{5}}\)
\(f,\sqrt{\dfrac{3-\sqrt{5}}{2-\sqrt{3}}}\\ =\sqrt{\dfrac{\left(3-\sqrt{5}\right)\left(2+\sqrt{3}\right)}{4-3}}\\ =\sqrt{\left(3-\sqrt{5}\right)\left(2+\sqrt{3}\right)}\\ =\sqrt{\dfrac{\left(6-2\sqrt{5}\right)\left(4+2\sqrt{3}\right)}{4}}\\ =\dfrac{\left(\sqrt{5}-1\right)\left(\sqrt{3}+1\right)}{2}\)
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\(a,\sqrt{3+\sqrt{5}}\left(\sqrt{10}+\sqrt{2}\right)\left(3-\sqrt{5}\right)\\ =\sqrt{3+\sqrt{5}}.\sqrt{3-\sqrt{5}}.\sqrt{3-\sqrt{5}}.\sqrt{2}\left(\sqrt{5}+1\right)\\ =\sqrt{\left(3+\sqrt{5}\right)\left(3-\sqrt{5}\right)}.\sqrt{6-2\sqrt{5}}.\left(\sqrt{5}+1\right)\\ =\sqrt{9-5}.\sqrt{\left(\sqrt{5}-1\right)^2}.\left(\sqrt{5}+1\right)\\ =2\left(\sqrt{5}-1\right)\left(\sqrt{5}+1\right)\\ =2.4\\ =8\)
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\(d,\left(2\sqrt{4+\sqrt{6-2\sqrt{5}}}\right)\left(\sqrt{10}-\sqrt{2}\right)\\ =\left(2\sqrt{4+\sqrt{\left(\sqrt{5}-1\right)^2}}\right)\sqrt{2}\left(\sqrt{5}-1\right)\\ =\left(2\sqrt{4+\sqrt{5}-1}\right)\sqrt{2}\left(\sqrt{5}-1\right)\\ =\sqrt{24+8\sqrt{5}}\left(\sqrt{5}-1\right)\\ =\sqrt{\left(2\sqrt{5}+2\right)^2}\left(\sqrt{5}-1\right)\\ =2\left(\sqrt{5}+1\right)\left(\sqrt{5}-1\right)\\ =2\left(5-1\right)\\ =8\)
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Xem thêm câu trả lời
1,Rút gọn
a, left(2sqrt{2}-1right)left(sqrt{8}+1right)
b, left(sqrt{12}+sqrt{75}-2sqrt{27}right):sqrt{3}
c, sqrt{3+2sqrt{2}}+sqrt{6-4sqrt{2}}
d, sqrt{6+2sqrt{5}}+sqrt{6-2sqrt{5}}
e, left(sqrt{3}-sqrt{2}right)sqrt{5+2sqrt{6}}
f, sqrt{8-2sqrt{15}}-sqrt{23-4sqrt{15}}
Đọc tiếp
1,Rút gọn
a, \(\left(2\sqrt{2}-1\right)\left(\sqrt{8}+1\right)\)
b, \(\left(\sqrt{12}+\sqrt{75}-2\sqrt{27}\right):\sqrt{3}\)
c, \(\sqrt{3+2\sqrt{2}}+\sqrt{6-4\sqrt{2}}\)
d, \(\sqrt{6+2\sqrt{5}}+\sqrt{6-2\sqrt{5}}\)
e, \(\left(\sqrt{3}-\sqrt{2}\right)\sqrt{5+2\sqrt{6}}\)
f, \(\sqrt{8-2\sqrt{15}}-\sqrt{23-4\sqrt{15}}\)
1. Tính ( rút gọn)a)sqrt{left(5-sqrt{19}right)^2}-sqrt{left(4-sqrt{19}right)^2}b)sqrt{left(3-2sqrt{2}right)^2}-sqrt{left(2sqrt{2}-3right)^2}c)sqrt{8+2sqrt{15}}+sqrt{left(sqrt{2-sqrt{5}}right)^2}d)sqrt{12+6sqrt{3}}.left(3+sqrt{3}right)e) left(2-sqrt{5}right).sqrt{9+4sqrt{5}}
Đọc tiếp
1. Tính ( rút gọn)
a)\(\sqrt{\left(5-\sqrt{19}\right)^2}-\sqrt{\left(4-\sqrt{19}\right)^2}\)
b)\(\sqrt{\left(3-2\sqrt{2}\right)^2}-\sqrt{\left(2\sqrt{2}-3\right)^2}\)
c)\(\sqrt{8+2\sqrt{15}}+\sqrt{\left(\sqrt{2-\sqrt{5}}\right)^2}\)
d)\(\sqrt{12+6\sqrt{3}}.\left(3+\sqrt{3}\right)\)
e) \(\left(2-\sqrt{5}\right).\sqrt{9+4\sqrt{5}}\)
a: Ta có: \(\sqrt{\left(5-\sqrt{19}\right)^2}-\sqrt{\left(4-\sqrt{19}\right)^2}\)
\(=5-\sqrt{19}-\sqrt{19}+4\)
\(=9-2\sqrt{19}\)
b: Ta có: \(\sqrt{\left(3-2\sqrt{2}\right)^2}-\sqrt{\left(2\sqrt{2}-3\right)^2}\)
\(=3-2\sqrt{2}-3+2\sqrt{2}\)
=0
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c.
Căn bậc 2 không xác định do $2-\sqrt{5}< 0$
d.
\(=\sqrt{(3+\sqrt{3})^2}(3+\sqrt{3})=|3+\sqrt{3}|(3+\sqrt{3})=(3+\sqrt{3})^2=12+6\sqrt{3}\)
e.
\(=(2-\sqrt{5})\sqrt{(2+\sqrt{5})^2}=(2-\sqrt{5})|2+\sqrt{5}|=(2-\sqrt{5})(2+\sqrt{5})=4-5=-1\)
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