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\(10+\sqrt{60}-\sqrt{24}-\sqrt{40}\)
\(=10+2\sqrt{15}-2\sqrt{6}-2\sqrt{10}\)
\(=10+2\sqrt{3}.\sqrt{5}-2\sqrt{2}.\sqrt{3}-2\sqrt{2}.\sqrt{5}\)
\(=3+5+2+...\)
\(=\left(\sqrt{3}+\sqrt{5}-\sqrt{2}\right)^2\)
\(\Rightarrow P=-\sqrt{2}+\sqrt{3}+\sqrt{5}\)
\(P=\sqrt{\left(\sqrt{2}+\sqrt{5}+\sqrt{7}\right)^2}=\left|\sqrt{2}+\sqrt{5}+\sqrt{7}\right|=\sqrt{2}+\sqrt{5}+\sqrt{7}\)
\(\sqrt{14+\sqrt{40}+\sqrt{56}+\sqrt{140}}\)
\(=\sqrt{2+5+7+2\sqrt{2.5}+2\sqrt{2.7}+2\sqrt{5.7}}\)
\(=\sqrt{\left(\sqrt{2}+\sqrt{5}+\sqrt{7}\right)^2}=\sqrt{2}+\sqrt{5}+\sqrt{7}\)
\(\Rightarrow a+b+c=2+5+7=14\)
\(=\left(2\sqrt{3}+3\sqrt{2}\right)\sqrt{5}+\sqrt{2^3\sqrt{3}}\)
Ta có √[ 5 + 2 + 3 + 2√(2×3) + 2√(2×5) + 2√(3×5)] = √[(√2 + √3 + √5)2] = √2 + √3 + √5
a/ \(\sqrt{2}+\sqrt{6}\)
b/ Sửa đề:
\(\sqrt{2+\sqrt{3}}.\sqrt{2+\sqrt{2+\sqrt{3}}}.\sqrt{2+\sqrt{2+\sqrt{2+\sqrt{3}}}}.\sqrt{2-\sqrt{2+\sqrt{2+\sqrt{3}}}}=1\)
c/ \(1+\sqrt{2}+\sqrt{5}\)
a) \(\sqrt{117^2-108^2}=\sqrt{\left(117-108\right)\left(117+108\right)}=\sqrt{9\cdot225}=\sqrt{3^2\cdot15^2}=\left|3\cdot15\right|=45\)
b) \(\sqrt{9-4\sqrt{5}}+2=\sqrt{5-4\sqrt{5}+4}+2=\sqrt{\left(\sqrt{5}-2\right)^2}+2=\left|\sqrt{5}-2\right|+2=\sqrt{5}\)
\(a,\sqrt{117^2-108^2}\\ =\sqrt{\left(117-108\right)\left(117+108\right)}\\ =\sqrt{9.225}\\ =\sqrt{3^2}.\sqrt{15^2}\\ =3.15\\ =45\)
\(b,\sqrt{9-4\sqrt{5}}+2=\sqrt{5}\)
\(VT=\sqrt{9-4\sqrt{5}}+2\\ =\sqrt{\sqrt{5^2}-2.2\sqrt{5}+2^2}+2\\ =\sqrt{\left(\sqrt{5}-2\right)^2}+2\\ =\left|\sqrt{5}-2\right|+2\\ =\sqrt{5}-2+2\\ =\sqrt{5}=VP\left(dpcm\right)\)
Bạn áp dụng hằng đẳng thức (a+b+c)^2= a^2+b^2+c^2+2(ab+ac+bc)
Ta có
\(P=\sqrt{14+2\sqrt{10}+2\sqrt{14}+2\sqrt{35}}\)
\(\Leftrightarrow P=\sqrt{\left(\sqrt{5}+\sqrt{2}+\sqrt{7}\right)^2}\)
\(\Leftrightarrow P=\sqrt{5}+\sqrt{2}+\sqrt{7}\)
Mà \(P=\sqrt{a}+\sqrt{b}+\sqrt{c}=\sqrt{5}+\sqrt{2}+\sqrt{7}\)
Suy ra \(a+b+c=5+2+7=14\)
\(A=\sqrt{10+\sqrt{24}+\sqrt{40}+\sqrt{60}}\)
\(=\sqrt{10+2\sqrt{6}+2\sqrt{10}+2\sqrt{15}}\)
\(=\sqrt{2+3+5+2\left(\sqrt{2.3}+\sqrt{2.5}+\sqrt{3.5}\right)}\)
\(=\sqrt{\left(\sqrt{2}+\sqrt{3}+\sqrt{5}\right)^2}\)
\(=\sqrt{2}+\sqrt{3}+\sqrt{5}\)