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a) \(A=\frac{1}{2}\sqrt{32}+\sqrt{98}-\frac{1}{6}\sqrt{18}=\frac{1}{2}\sqrt{4^2.2}+\sqrt{7^2.2}-\frac{1}{6}.\sqrt{3^2.2}\)
\(=\frac{1}{2}\sqrt{4^2}.\sqrt{2}+\sqrt{7^2}.\sqrt{2}-\frac{1}{6}.\sqrt{3^2}.\sqrt{2}\)\(=\frac{1}{2}.4\sqrt{2}+7\sqrt{2}-\frac{1}{6}.3.\sqrt{2}\)\(=2.\sqrt{2}+7\sqrt{2}-\frac{1}{2}\sqrt{2}=\left(2+7-\frac{1}{2}\right)\sqrt{2}=\frac{17}{2}\sqrt{2}\)
a) \(\sqrt{6+2\sqrt{5}}+\sqrt{6-2\sqrt{5}}=\sqrt{1+2\sqrt{5}+\left(\sqrt{5}\right)^2}+\sqrt{1-2\sqrt{5}+\left(\sqrt{5}\right)^2}\)\(=\sqrt{\left(1+\sqrt{5}\right)^2}+\sqrt{\left(1-\sqrt{5}\right)^2}=1+\sqrt{5}-\left(1-\sqrt{5}\right)=1+\sqrt{5}-1+\sqrt{5}=2\sqrt{5}\)
a) \(\sqrt{6+2\sqrt{5}}+\sqrt{6-2\sqrt{5}}\)
\(=\sqrt{\left(\sqrt{5}+1\right)^2}+\sqrt{\left(\sqrt{5}-1\right)^2}\)
\(=\sqrt{5}+1+\sqrt{5}-1=2\sqrt{5}\)
b) \(\sqrt{13+4\sqrt{10}}+\sqrt{13-4\sqrt{10}}\)
\(=\sqrt{\left(2\sqrt{2}+\sqrt{5}\right)^2}+\sqrt{\left(2\sqrt{2}-\sqrt{5}\right)^2}\)
\(=2\sqrt{2}+\sqrt{5}+2\sqrt{2}-\sqrt{5}=4\sqrt{2}\)
c) \(\sqrt{8\sqrt{3}}-2\sqrt{25\sqrt{12}}+4\sqrt{\sqrt{192}}\)
\(=2\sqrt{2\sqrt{3}}-10\sqrt{2\sqrt{3}}+8\sqrt{2\sqrt{3}}=0\)
\(a,\sqrt{mn}+1+\sqrt{m}+\sqrt{n}\)
\(=\sqrt{mn}+\sqrt{m}+\sqrt{n}+1\)
\(=\sqrt{m}\left(\sqrt{n}+1\right)+\sqrt{n}+1\)
\(=\left(\sqrt{n}+1\right)\left(\sqrt{m}+1\right)\)
\(b,a+b-2\sqrt{ab}-25\)
\(=\left(\sqrt{a}-\sqrt{b}\right)^2-5^2\)
\(=\left(\sqrt{a}-\sqrt{b}-5\right)\left(\sqrt{a}-\sqrt{b}+5\right)\)
\(c,m-2\sqrt{m}-3\)
\(=m-2\sqrt{m}+1-4\)
\(=\left(\sqrt{m}-1\right)^2-2^2\)
\(=\left(\sqrt{m}-1+2\right)\left(\sqrt{m}-1-2\right)\)
\(=\left(\sqrt{m}+1\right)\left(\sqrt{m}-3\right)\)
\(d,a+6\sqrt{a}+8\)
\(=a+6\sqrt{a}+9-1\)
\(=\left(\sqrt{a}+3\right)^2-1\)
\(=\left(\sqrt{a}+3+1\right)\left(\sqrt{a}+3-1\right)\)
\(=\left(\sqrt{a}+4\right)\left(\sqrt{a}+2\right)\)
\(e,\sqrt{m}-m^2=\sqrt{m}\left[1-\left(\sqrt{m}\right)^3\right]\)
\(=\sqrt{m}\left(1-\sqrt{m}\right)\left(1+\sqrt{m}+m\right)\)
\(f,p^2+\sqrt{p}=\sqrt{p}\left[\left(\sqrt{p}\right)^3+1\right]\)
\(=\sqrt{p}\left(\sqrt{p}+1\right)\left(p-\sqrt{p}+1\right)\)
=.= hok tốt !!
hihi
a)\(a-b=\left(\sqrt{a}-\sqrt{b}\right)\left(\sqrt{a}+\sqrt{b}\right)\)
b)\(=\sqrt{ab}\left(\sqrt{a}+\sqrt{b}\right)\)
c) \(\sqrt{a}^3-\sqrt{b}^3=\left(\sqrt{a}-\sqrt{b}\right)\left(a+\sqrt{ab}+b\right)\)
a) \(a-b=-\left(b-a\right)=a+\left(-b\right)\)
b) \(a\sqrt{b}+b\sqrt{a}=b\sqrt{a}+a\sqrt{b}\)
c) \(a\sqrt{a}-b\sqrt{b}=-\left(b\sqrt{b}-a\sqrt{a}\right)=a\sqrt{a}+\left(-b\sqrt{b}\right)\)
a, \(5+\sqrt{5}=\sqrt{5}\left(\sqrt{5}+1\right)\)
b, \(a-2\sqrt{a}=\sqrt{a}\left(\sqrt{a}-2\right)\)
c, \(x-\sqrt{xy}=\sqrt{x}\left(\sqrt{x}-\sqrt{y}\right)\)
d, \(x-y-\sqrt{x}-\sqrt{y}\)
\(=\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)-\left(\sqrt{x}+\sqrt{y}\right)\)
\(=\left(\sqrt{x}+\sqrt{y}\right)\left(\sqrt{x}-\sqrt{y}-1\right)\)
\(\text{a) }\sqrt{a^3+b^3}+\sqrt{a^2-b^2}=\sqrt{\left(a+b\right)\left(a^2-ab+b^2\right)}+\sqrt{\left(a+b\right)\left(a-b\right)}\)
\(=\sqrt{a+b}\left(\sqrt{a^2-ab+b^2}+\sqrt{a-b}\right)\)
\(\text{b) }\sqrt{ax}-\sqrt{by}+\sqrt{bx}-\sqrt{xy}\text{ không phân tích được.}\)
\(\text{c) }=\left(\sqrt{x}-\sqrt{y}\right)\left(x+\sqrt{xy}+y\right)+\left(\sqrt{x}-\sqrt{y}\right).\sqrt{xy}\)
\(=\left(\sqrt{x}-\sqrt{y}\right)\left(x+y+2\sqrt{xy}\right)\)\(=\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)^2\)
\(\text{d) }a+5\sqrt{a}+4=\sqrt{a}.\sqrt{a}+\sqrt{a}+4\sqrt{a}+4=\sqrt{a}\left(\sqrt{a}+1\right)+4\left(\sqrt{a}+1\right)\)
\(=\left(\sqrt{a}+1\right)\left(\sqrt{a}+4\right)\)
a,\(x\sqrt{y}+y\sqrt{x}=\sqrt{x}\sqrt{y}.\left(\sqrt{x}+\sqrt{y}\right).\)
c,\(\sqrt{a}-a^2=\sqrt{a}.\left(1-a\sqrt{a}\right)\)
d,\(x-5\sqrt{x}+6=x-3\sqrt{x}-2\sqrt{x}+6\)
\(=\sqrt{x}.\left(\sqrt{x}-3\right)-2.\left(\sqrt{x}-3\right)\)\(=\left(\sqrt{x}-3\right).\left(\sqrt{x}-2\right)\)
a) \(5+\sqrt{10}-\sqrt{5}=\sqrt{5}.\left(\sqrt{5}+\sqrt{2}-1\right)\)
b) ĐK: \(a\ge0\)
\(a-4\sqrt{a}-5=a+\sqrt{a}-5\sqrt{a}-5=\left(\sqrt{a}+1\right)\left(\sqrt{a}-5\right)\)
c) ĐK: \(a\ge0\)
\(a+12\sqrt{a}+32=a+8\sqrt{a}+4\sqrt{a}+32=\left(\sqrt{a}+8\right)\left(\sqrt{a}+4\right)\)
d) ĐK: \(a\ge0\)
\(a-5\sqrt{a}+6=a-2\sqrt{a}-3\sqrt{a}+6=\left(\sqrt{a}-2\right)\left(\sqrt{a}-3\right)\)