tìm x để A nguyên dương bt A=x^2/(x^2-4)

\(\sqrt{4-\sqrt{7}}-\sqrt{4+\sqrt{7}}\)

\(\sqrt{2-\sqrt{3}}\left(\sqrt{6}+\sqrt{2}\right)\)

\(\left\{{}\begin{matrix}2x+y=5m-1\\x-2y=2\end{matrix}\right.\)

tìm m để hệ có no (x;y) tm x^2+2y^2=2

tìm x

` ((-3)^x .3^6)/(-27.9^x) =-3`

\(\left\{{}\begin{matrix}\dfrac{108}{x+y}+\dfrac{63}{x-y}=4\\\dfrac{81}{x+y}+\dfrac{84}{x-y}=7\end{matrix}\right.\)

ptdttnt

x^4+2x^2+1

4x^2-12xy+9y^2

-x^2 -2xy-y^2

(x+y)^2-2(x+y)+1

x^3-3x^2+3x-1

x^3+6x^2+12x+8

x^3+1-x^2-x

(x+y)^3-x^3-y^3

ptdttnt

a(b+c)(b^2-c^2)+b(c+a)(c^2-a^2)+c(a+b)(a^2-b^2)