(3x -3y)² -(2x - 3y)² = ( 3x-3y  -2x+3y)(3x -3y + 2x - 3y) = x.(5x-6y)

x² + 2x + 1 = (x+1)²

x^2-25

(x-5)(x-5) = x² - 25

X² - 8x + 16 = x² - 2.x.4 + 4² = (x-4)²

\(AC^2=AD^2+DC^2=BD^2-AB^2+DC^2\)

\(4^2=2DC^2-3^2\)

\(BD=DC=BC=\dfrac{5}{\sqrt{2}}\)

\(AD^2=BD^2-3^2=\dfrac{25}{2}-3^2=\dfrac{7}{2}\)

\(C=AB+BC+CD+DA=3+\dfrac{5}{\sqrt{2}}+\dfrac{5}{\sqrt{2}}+\dfrac{\sqrt{7}}{\sqrt{2}}\)

\(S=\dfrac{\left(3+\dfrac{5}{\sqrt{2}}\right)\times\dfrac{\sqrt{7}}{\sqrt{2}}}{2}\)

\(T=\dfrac{3+\dfrac{5}{\sqrt{2}}}{2}\)

X² + 4X + 4 = X² + 2.2X + 2² = (X +2)²

`(x-y^2)^2`

`= x^2 - 2xy^2 +y^4`

\(\left(x-y^2\right)^2\)

\(=x^2+2.x.y^2+\left(y^2\right)^2\)

\(=x^2-2xy^2+y^4\)

Yêu cầu đề bài là gì vậy bạn?

`(6x+1)^{2}+(6x-1)^{2}-2.(1+6x)(6x-1)`

`=[(6x+1)-(6x-1)]^{2}`

`=(6x+1-6x+1)^{2}`

`=2^{2}=4`

`(x^{2}-y^{2})^{2}`

`=(x^{2})^{2}-2.x^{2}.y^{2}+(y^{2})^{2}`

`=x^{4}-2x^{2}y^{2}+y^{4}`