Question

[Nhi nè]

Bài 4: Cho các đa thức : A(x) = 3x6 – 5x4 +2x2– 7 B(x) = 8x6 + 7x4 – x2 + 11 C(x) = x6 + x4 – 8x2 + 6

Tính: A(x) + B(x);                 

  B(x) + C(x);              

   A(x) + C(x) A(x) + B(x)- C(x);                

   B(x) + C(x) – A(x); C(x) + A(x)  – B(x);             

   A(x) + B(x) + C(x)
 

Answer 1

[Nguyễn Huy Tú]

sửa hộ mình B(x) + C(x) là -9x^2

Ta có : \(B\left(x\right)+C\left(x\right)-A\left(x\right)\)

\(\Rightarrow9x^6+8x^4-9x^2+17-3x^6+5x^4+2x^2-7=6x^6+13x^4-7x^2+10\)

\(C\left(x\right)+A\left(x\right)-B\left(x\right)\)

\(\Rightarrow4x^6-4x^4-6x^2-1-8x^6-7x^4+x^2-11=-4x^6-11x^4-5x^2-12\)

\(A\left(x\right)+B\left(x\right)+C\left(x\right)\Rightarrow11x^6+2x^4+x^2+4+x^6+x^4-8x^2+6\)

\(=12x^6+3x^4-7x^2+10\)

Answer 2

[Nguyễn Huy Tú]

Ta có : \(A\left(x\right)+B\left(x\right)\Rightarrow3x^6-5x^4+2x^2-7+8x^6+7x^4-x^2+11\)

\(=11x^6+2x^4+x^2+4\)

\(B\left(x\right)+C\left(x\right)\Rightarrow8x^6+7x^4-x^2+11+x^6+x^4-8x^2+6\)

\(=9x^6+8x^4-10x^2+17\)

\(A\left(x\right)+C\left(x\right)\Rightarrow3x^6-5x^4+2x^2-7+x^6+x^4-8x^2+6\)

\(=4x^6-4x^4-6x^2-1\)

\(B\left(x\right)-C\left(x\right)\Rightarrow8x^6+7x^4-x^2+11-x^6-x^4+8x^2-6\)

\(=7x^6+6x^4+7x^2+5\)