Question

Bài 2 Phân tích đa thức thành nhân tử

a) \(5+\sqrt{5}\)

b) a - \(2\sqrt{a}\)

c ) \(x-\sqrt{xy}\) ( với x,y > 0 )

d) \(x-y-\sqrt{x}-\sqrt{y}\)

Answer 1

a= 98 b=35 c=122 và d=129

Answer 2

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, \(x-y-\sqrt{x}-\sqrt{y}\)

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

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

Answer 3

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

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

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