hơi dài, thôi chăm chỉ tí có sao :v =))
\(A=-x^3\left(3x-1\right)-x\left(1+3x^4\right)-x^2\left(x^2-x-2\right)\)
\(=-3x^4+x^3-x-3x^5-x^4+x^3+2x^2\)
\(=-4x^4+2x^3-x-3x^5+2x^2\)
\(B=-x^2\left(2x^2-2x-4\right)-2x\left(2-4x^4\right)-2x^3\left(2x-2\right)\)
\(=-2x^3+2x^3+4x^2-4x+8x^5-4x^4+4x^3\)
\(=4x^2-4x+8x^5-4x^4+4x^3\)
Ta có : \(A-B=-4x^4+2x^3-x-3x^5+2x^2-4x^2+4x-8x^5+4x^4-4x^3\)
\(=-2x^3+3x-11x^5-2x^2\)
Tương tự bn nhé, mk hơi bị đao phần đa thức khi qua kì thi nên hơi bị chậc lẫn một xíu =((
\(A=-x^3\left(3x-1\right)-x\left(1+3x^4\right)-x^2\left(x^2-x-2\right)\)
\(A=-3x^4+x^3-x-3x^5-x^4+x^3+2x^2\)
\(A=-3x^5-4x^4+2x^3+2x^2-x\)
\(B=-x^2\left(2x^2-2x-4\right)-2x\left(2-4x^4\right)-2x^3\left(2x-2\right)\)
\(B=-2x^4+2x^3+4x^2-4x+8x^5-4x^4+4x^3\)
\(B=8x^5-6x^4+6x^3+4x^2-4x\)
Tớ bảo mà =(( +;- đa thức bị executioner
\(B=-x^2\left(2x^2-2x-4\right)-2x\left(2-4x^4\right)-2x^3\left(2x-2\right)\)
\(=-2x^4+2x^3+4x^2-4x+8x^5-4x^4+4x^3\)
\(=-6x^4+6x^3+4x^2-4x+8x^5\)
Ta có : \(A-B=-4x^4+2x^3-x-3x^5+2x^2+6x^4-6x^3-4x^2+4x-8x^5\)
\(=2x^4-4x^3+3x-11x^5-2x^2\)
\(A-B=\left(-3x^5-4x^4+2x^3+2x^2-x\right)-\left(8x^5-6x^4+6x^3+4x^2-4x\right)\)
\(=-3x^5-4x^4+2x^3+2x^2-x-8x^5+6x^4-6x^3-4x^2+4x\)
\(=-11x^5+2x^4-4x^3-2x^2+3x\)
\(B-A=\left(8x^5-6x^4+6x^3+4x^2-4x\right)-\left(-3x^5-4x^4+2x^3+2x^2-x\right)\)
\(=8x^5-6x^4+6x^3+4x^2-4x+3x^5+4x^4-2x^3-2x^2+x\)
\(=11x^5-2x^4+4x^3+2x^2-3x\)
\(A+B=\left(-3x^5-4x^4+2x^3+2x^2-x\right)+\left(8x^5-6x^4+6x^3+4x^2-4x\right)\)
\(=-3x^5-4x^4+2x^3+2x^2-x+8x^5-6x^4+6x^3+4x^2-4x\)
\(=5x^5-10x^4+8x^3+6x^2-5x\)
\(-A=B\Leftrightarrow-\left(-3x^5-4x^4+2x^3+2x^2-x\right)=\left(8x^5-6x^4+6x^3+4x^2-4x\right)\)
\(\Leftrightarrow3x^5+4x^4-2x^3-2x^2+x=8x^5-6x^4+6x^3+4x^2-4x\)
\(\Leftrightarrow3x^5+4x^4-2x^3-2x^2+x-8x^5+6x^4-6x^3-4x^2+4x=0\)
\(\Leftrightarrow-5x^5+10x^4-8x^3-6x^2+5x=0\)
Đến đây tịt rồi =)
