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

\(\left(\dfrac{2}{3}\right)^2\left(\dfrac{2}{3}\right)^4=\left(\dfrac{2}{3}\right)^{2+4}=\left(\dfrac{2}{3}\right)^6=\dfrac{2^6}{3^6}=\dfrac{64}{729}\)

4/9

16/27

`b) ( -3xy^2)^2 . 2 / 3 xy^2`

`= 9x^2y^4 . 2 / 3 xy^2`

`= ( 9 . 2 / 3 ) ( x^2 . x ) ( y^4 . y^2 )`

`= 6x^3y^6`

\(=9x^2y^4.\dfrac{2}{3}xy^2=\left(9.\dfrac{2}{3}\right).\left(x^2.x\right).\left(y^4.y^2\right)=6x^3y^6\)

\(A=3x^2y-4xy+6x^2y+4xy=9x^2y\)

`@` `\text {Ans}`

`\downarrow`

`A = `\(3x^2y-4xy+6x^2y+4xy \)

`= (3x^2y + 6x^2y) + (-4xy + 4xy)`

`= 9x^2y + 0`

`= 9x^2y`

`@` `\text {Kaizuu lv uuu}`

cái này mik lm ròi mà bạn

https://hoc24.vn/cau-hoi/cho-da-thuc-a-4x3-35x2y2-3x3-35x2y2-7xy-1a-rut-gon-da-thuc-va-tim-bacb-thu-gon-da-thuc.5830672960238

\(x(x-1)(x+1)-(x-3)(x^2+2x+9)\)

\(=x\left(x^2-1\right)-\left[x\left(x^2+2x+9\right)-3\left(x^2+2x+9\right)\right]\)

\(=x^3-x-\left(x^3+2x^2+9x-3x^2-6x-27\right)\)

\(=x^3-x-\left(x^3-x^2+3x-27\right)\)

\(=x^3-x-x^3+x^2-3x+27\)

\(=x^2-4x+27\)

#\(Toru\)

Đề đâu ah.

Đề là như vậy hay là \(B=8\sqrt{20+2\sqrt{43+24\sqrt{3}}}\) vậy em?

Căn thức phải trùm hết \(24\sqrt{3}\) với hợp lý chứ nhỉ?

\(B=8\sqrt{20+2\sqrt{43+24\sqrt{3}}}\)

\(=8\sqrt{20+2\sqrt{\left(3\sqrt{3}+4\right)^2}}\)

\(=8\sqrt{20+2\left(3\sqrt{3}+4\right)}\)

\(=8\sqrt{28+6\sqrt{3}}\)

\(=8\sqrt{\left(3\sqrt{3}+1\right)^2}\)

\(=8\left(3\sqrt{3}+1\right)=8+24\sqrt{3}\)

\(=-15ax^3y^5z\)

Hệ só là -15a