Question

a)     \(^{â^3-2\sqrt{2}}\)

b)\(\sqrt{21}+\sqrt{3}+\sqrt{7}+1\)

 c)  \(x+2\sqrt{x}-3\)

Answer 1

đề là j b

Answer 2

rút gọn 

Answer 3

a) \(a^3-2\sqrt{2}\)

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

\(=\left(a-\sqrt{2}\right)\left(a+a\sqrt{2}+2\right)\)

b)  \(\sqrt{21}+\sqrt{3}+\sqrt{7}+1\)

\(=\sqrt{3}\left(\sqrt{7}+1\right)+\left(\sqrt{7}+1\right)\)

\(=\left(\sqrt{7}+1\right)\left(\sqrt{3}+1\right)\)

c)  \(x+2\sqrt{x}-3\)

\(=x-\sqrt{x}+3\sqrt{x}-3\)

\(=\sqrt{x}\left(\sqrt{x}-1\right)+3\left(\sqrt{x}-1\right)\)

\(=\left(\sqrt{x}-1\right)\left(\sqrt{x}+3\right)\)