\(a,=x^2-9-x^2+6x-9=6x-18\\ b,=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)=\left(x+y-5\right)\left(x-y\right)\)

b. 5x + 5y - 3x - 3y

= (5x - 3x) + (5y - 3y)

= 2x + 2y

= 2(x + y)

a) \(3a-2\sqrt{ab}-b=3a-3\sqrt{ab}+\sqrt{ab}-b\)

\(=3\sqrt{a}\left(\sqrt{a}-\sqrt{b}\right)+\sqrt{b}\left(\sqrt{a}-\sqrt{b}\right)=\left(3\sqrt{a}+\sqrt{b}\right)\left(\sqrt{a}-\sqrt{b}\right)\)

b) \(5a+3\sqrt{ab}-8b=5a-5\sqrt{ab}+8\sqrt{ab}-8b\)

\(=5\sqrt{a}\left(\sqrt{a}-\sqrt{b}\right)+8\sqrt{b}\left(\sqrt{a}-\sqrt{b}\right)\)

\(=\left(5\sqrt{a}+8\sqrt{b}\right)\left(\sqrt{a}-\sqrt{b}\right)\)

a) (\(\sqrt{a}-\sqrt{b}\))(3\(\sqrt{a}+b\))

b) \(\left(\sqrt{a}-\sqrt{b}\right)\left(5\sqrt{a}+8\sqrt{b}\right)\)

a/\(\left(\sqrt{a}-\sqrt{b}\right)\left(3\sqrt{a}+\sqrt{b}\right)\)

b/ \(\left(\sqrt{a}-\sqrt{b}\right)\left(5\sqrt{a}+8\sqrt{b}\right)\)

a) xy+3x-7y-21

=x(y+3)-7(x+3)

=(x-7)(y+3)

b)2xy-15-6x-5y

=2x(y-3)-5(-3+y)

=(2x-5)(y-3)

c)2x^2y+2xy^2-2x-2y

=2x(xy-1)+2y(xy-1)

=(2x+2y)(xy-1)

x(x+3)-5x(x-5)-5(x+3)

=(x-5)(x+3)-5x(x-5)

=(x-5)(x+3-5x)

Câu cuối mình bị nhầm dòng cuối phải là (x-5)(x+3+x-5)=(x-5)(2x-2)nha bạn

a) xy+3x-7y-21=(xy+3x)-(7y+21)= x(y+3)-7(y+3)=(y+3)(x-7)

b)2xy-15-6x+5y=(2xy-6x)+(5y-15)=2x(y-3)+5(y-3)=(y-3)(2x+5)

c)2x^2y+2xy^2-2x-2y=2xy(x+y)-2(x+y)=2(x+y)(xy-1)

d) x(x+3)-5x(x-5)-5(x+3)=[x(x+3)-5(x+3)]-5x(x-5)=(x+3)(x-5)-5x(x-5)=(x-5)(x+3-5x)=(x-5)(3-4x)

a: \(A=x\sqrt{x}-y\sqrt{y}+x\sqrt{y}-y\sqrt{x}\)

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

\(=\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)^2\)

b: \(B=5x^2-7x\sqrt{y}+2y\)

\(=5x^2-5x\sqrt{y}-2x\sqrt{y}+2y\)

\(=5x\left(x-\sqrt{y}\right)-2\sqrt{y}\left(x-\sqrt{y}\right)\)

\(=\left(x-\sqrt{y}\right)\left(5x-2\sqrt{y}\right)\)

a: \(=3\left[\left(m-5\right)^3+8\right]\)

\(=3\left(m-5+2\right)\left[\left(m-5\right)^2-2\left(m-5\right)+4\right]\)

\(=3\left(m-3\right)\left(m^2-10m+25-2m+10+4\right)\)

\(=3\left(m-3\right)\left(m^2-12m+39\right)\)

b: \(=5\left(1-6k\right)^3-5\cdot64\)

\(=5\left(1-6k-4\right)\left[\left(1-6k\right)^2+4\left(1-6k\right)+16\right]\)

\(=5\left(-6k-3\right)\left(36k^2-12k+1+4-24k+16\right)\)

\(=-15\left(2k+1\right)\left(36k^2-36k+21\right)\)

\(=-45\left(2k+1\right)\left(12k^2-12k+7\right)\)

c: \(=\left(a+b-2b+a\right)\left[\left(a+b\right)^2+\left(a+b\right)\left(2b-a\right)+\left(2b-a\right)^2\right]\)

\(=\left(2a-b\right)\left(a^2+2ab+b^2+2ab-a^2+2b^2-ab+4b^2-4ab+b^2\right)\)

\(=\left(2a-b\right)\cdot b\cdot\left(6b+a\right)\)