Question

Phân tích thành nhân tử:

a) a - 5√a

b) a - 7 với a > 0

c) a + 4√a + 4

d) √xy - 4√x + 3√y - 12

Answer 1

a) \(a-5\sqrt{a}\)

\(=\sqrt{a}\left(\sqrt{a}-\sqrt{5}\right)\)

b) \(a-7\)

\(=\left(\sqrt{a}-\sqrt{7}\right)\left(\sqrt{a}+\sqrt{7}\right)\)

c) \(a+4\sqrt{a}+4\)

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

d) \(\sqrt{xy}-4\sqrt{x}+3\sqrt{y}-12\)

\(=\sqrt{x}\left(\sqrt{y}-4\right)+3\left(\sqrt{y}-4\right)\)

\(=\left(\sqrt{x}+3\right)\left(\sqrt{y}-4\right)\)

Answer 2

a: \(a-5\sqrt{a}=\sqrt{a}\left(\sqrt{a}-5\right)\)

b: \(a-7=\left(\sqrt{a}-\sqrt{7}\right)\left(\sqrt{a}+\sqrt{7}\right)\)

c: \(a+4\sqrt{a}+4=\left(\sqrt{a}+2\right)^2\)

d: \(\sqrt{xy}-4\sqrt{x}+3\sqrt{y}-12\)

=căn x(căn y-4)+3(căn y-4)

=(căn y-4)(căn x+3)

Answer 3

\(a,a-5\sqrt{a}=\sqrt{a}\left(\sqrt{a}-5\right)\\ b,a-7=\left(\sqrt{a}\right)^2-\left(\sqrt{7}\right)^2=\left(\sqrt{a}-\sqrt{7}\right)\left(\sqrt{a}+\sqrt{7}\right)\\ c,a+4\sqrt{a}+4=\left(\sqrt{a}\right)^2+2\sqrt{a}.2+2^2=\left(\sqrt{a}+2\right)^2\\ d,Sửa.đề:\sqrt{x}.\sqrt{y}-4\sqrt{x}+3\sqrt{y}-12\\ =\sqrt{x}\left(\sqrt{y}-4\right)+3.\left(\sqrt{y}-4\right)=\left(\sqrt{x}+3\right)\left(\sqrt{y}-4\right)\)

Answer 4

`a)a-5\sqrta`

`=\sqrta(\sqrta-5)`

`b)a-7`

`=(\sqrta-\sqrt7)(\sqrta+\sqrt7)`

`c)a+4\sqrta+4`

`=(\sqrta+2)^2`

`d)\sqrt{xy}-4\sqrtx+3\sqrty-12`

`=\sqrtx(\sqrty-4)+3(\sqrty-4)`

`=(\sqrtx+3)(\sqrty-4)`