\(\left(5-3x\right)^3-\left(x+8\right)\left(x-8\right)+\left(3-x\right)^2\)

\(=\left(125-225x+135x^2-27x^3\right)-\left(x^2-64\right)+\left(9-6x+x^2\right)\)

\(=125-225x+135x^2-27x^3-x^2+64+9-6x+x^2\)

\(=-27x^3+135x^2-231x+198\)

xin lỗi, hiểu lầm, tại bạn ko ghi rõ

???????????????????????????????????????????????

\(x^2-16-4xy+4y^2\)

\(=\left(x^2-2.x.2y+2y^2\right)-4^2\)

\(=\left(x-2y\right)^2-4^2\)

\(=\left(x-2y-4\right)\left(x-2y+4\right)\)

xong xài hđt số 3 ak???

 a)   \(45+x^3-5x^2-9x\)

\(\Leftrightarrow\left(45-9x\right)+\left(x^3-5x^2\right)\)

\(\Leftrightarrow-9\left(x-5\right)+x^2\left(x-5\right)\) 

\(\Leftrightarrow\left(x-5\right)\left(x-3\right)\left(x+3\right)\) 

TK NKA !!!

xnxx.com

Ta có : \(a+b+c=0\Rightarrow\)\(a+b=-c\Leftrightarrow-\left(a+b\right)=c\)

\(\Rightarrow a^3+b^3+c^3=a^3+b^3+\left[-\left(a+b\right)\right]^3\)

\(\Leftrightarrow a^3+b^3-\left[a^3+3ab\left(a+b\right)+b^3\right]\)

\(\Leftrightarrow a^3+b^3-a^3-3ab\left(a+b\right)-b^3\)

\(=-3ab \left(a+b\right)\)\(\Rightarrow-3ab\left(-c\right)=3abc\Rightarrow3.\left(-2\right)=-6\)

\(\Rightarrow a^3+b^3+c^3=-6\)

Đề phải là x^4-12x^3+12x^2-12x+111 tại x=11.

x=11

=>x+1=12

thay x+1=12 vào x^4-12x^3+12x^2-12x+111 ta được:

x⁴-(x+1)x³+(x+1)x²-(x+1)x+111

=x⁴-x⁴-x³+x³+x²-x²-x+111

=111-x

=111-12

=99

x+1=12

thay 'x+1=12 vào x^4-12x^3+12x^2-12x+111 ta có

x^4-(x+1)x^3+(x+1)x^2-(x+1)x+111

=x^4-x^4-x^3+x^3+x^2-x^2-x+111

=111-x

=111-11

=100