\(B=\left[x\left(x+10\right)\right].\left[\left(x+4\right)\left(x+6\right)\right]+128=\left(x^2+10x\right)\left(x^2+4x+6x+24\right)+128\)

\(=\left(x^2+10x\right)\left(x^2+10x+24\right)+128\)

Đặt\(a=x^2+10x\Rightarrow a+24=x^2+10x+24\)

\(\Rightarrow B=a.\left(a+24\right)+128=a^2+24a+128=a^2+8a+16a+128\)

\(=a\left(a+8\right)+16\left(a+8\right)=\left(a+8\right)\left(a+16\right)=\left(x^2+10x+8\right)\left(x^2+10x+16\right)\)

\(=\left(x^2+10x+8\right)\left(x^2+2x+8x+16\right)=\left(x^2+10x+8\right)\left[x\left(x+2\right)+8\left(x+2\right)\right]\)

\(=\left(x+2\right)\left(x+8\right)\left(x^2+10x+8\right)\)

Xong hết !!!!!!!!!!

______CHÚC BẠN HỌC TỐT_________________

\(A=x^4+2x^3+x^2+4x^2+4x-12=x^4+2x^3+5x^2+4x-12\)

\(=x^4-x^3+3x^3-3x^2+8x^2-8x+12x-12\)

\(=x^3\left(x-1\right)+3x^2\left(x-1\right)+8x\left(x-1\right)+12\left(x-1\right)=\left(x-1\right)\left(x^3+3x^2+8x+12\right)\)

\(=\left(x-1\right)\left(x^3+2x^2+x^2+2x+6x+12\right)=\left(x-1\right)\left[x^2\left(x+1\right)+x\left(x+2\right)+6\left(x+2\right)\right]\)\(=\left(x-1\right)\left(x+2\right)\left(x^2+x+6\right)\)

trước 1 bài

B=-(x²-10x+25-20)=-[(x-5)²-20]=-(x-5)²+20 vậy GTLN là 20

sai đề nha bạn, tìm GTLN mới phải

x²  - 2xy + y² - z² + 2zt - t² 

= (x²  - 2xy + y²) - (z² - 2zt + t²)

= (x-y)^2  - (z - t)^2

= (x-y+z-t)(x-y-z-t)

chỉ có thể là \(\left(a+b\right)^2-2ab\)thôi bạn ơi

T I C K nha 

CHÚC BẠN HỌC TỐT

Trả lời hộ mình đi

=\(x^2-2xy+y^2-\left(z^2-2zt+t^2\right)\))

=\(\left(x-y\right)^2\)- \(\left(z-t\right)^2\)