\(M\left(x\right)=3x^4-2x^3+5x^2-4x+1\)

\(N\left(x\right)=-3x^4+2x^3-5x^2+7x+5\)

\(P\left(x\right)=M\left(x\right)+N\left(x\right)\)

\(=\left(3x^4-2x^3+5x^2-4x+1\right)+\left(-3x^4+2x^3-5x^2+7x+5\right)\)

\(=3x+6\)

\(Q\left(x\right)=M\left(x\right)-N\left(x\right)\)

\(=\left(3x^4-2x^3+5x^2-4x+1\right)-\left(-3x^4+2x^3-5x^2+7x+5\right)\)

\(=3x^4-2x^3+5x^2-4x+1+3x^4-2x^3+5x^2-7x-5\)

\(=6x^4-4x^3+10x^2-11x-4\)

a) \(M\left(x\right)=-2x^5+5x^2+7x^4-5x+8+2x^5-7x^4-4x^2+6\)

\(=\left(-2x^5+2x^5\right)+\left(7x^4-7x^4\right)+\left(5x^2-4x^2\right)-9x+\left(8+6\right)\)

\(=x^2-9x+14\)

\(N\left(x\right)=7x^7+x^6-5x^3+2x^2-7x^7+5x^3+3\)

\(=\left(7x^7-7x^7\right)+x^6-\left(5x^3-5x^3\right)+2x^2+3\)

\(=x^6+2x^2+3\)

b) Đa thức M(x) có hệ số cao nhất là 1 

                                hệ số tự do là 14

                                bậc 2

 Đa thức N(x) có hệ số cao nhất là 1 

                            hệ số tự do là 3 

                            bậc 6

f(x)=\(9-x^5-7x^4-2x^3+x^2+4x\)

g(x)=\(x^5-7x^4+4x^3-3x-9\)

f(x)+g(x)=\(9-x^5-7x^4-2x^3+x^2+4x\)+\(x^5-7x^4+4x^3-3x-9\)

=(9-9)-(\(x^5-x^5\))\(-\left(7x^4+7x^4\right)-\left(2x^3-4x^3\right)+x^2\)+(\(\)\(4x-3x\))

=\(-14x^4+2x^3+x^2+x\)

a) Sắp xếp các đa thức theo lũy thừa giảm của biến :

\(f\left(x\right)=-x^5-7x^4-2x^3+x^2+4x+9\)

\(g\left(x\right)=x^5-7x^4+2x^3+2x^3-3x-9\)

b, \(h\left(x\right)=f\left(x\right)+g\left(x\right)\)

\(=\left(-x^5-7x^4-2x^3+x^2+4x+9\right)+\left(x^5-7x^4+2x^3+2x^3-3x-9\right)\)

=> h(x) = -14x⁴ + 2x³ + x² +x

a)\(P\left(x\right)=M\left(x\right)+N\left(x\right)\)

\(P\left(x\right)=x^4+3x-\dfrac{1}{9}-x+3x^4+2x^2+8x-2x^3+2x^3+\dfrac{2}{3}+4x-4x^4-\dfrac{1}{3}\)

\(P\left(x\right)=2x^2+\dfrac{2}{9}+14x\)

rối lắm luôn

a)

`P(x)=7x^3+(4x^2-3x^2)-x+5=7x^3+x^2-x+5`

`Q(x)=-7x^3-x^2+2x+(6-8)=-7x^3-x^2+2x-2`

b)

`P(x)+Q(x) = 7x^3+x^2-x+5-7x^3-x^2+2x-2`

`=(7x^3-7x^3)+(x^2-x^2)+(2x-x)+(5-2)`

`=x+3`

`P(x)-Q(x)=7x^3+x^2-x+5-(-7x^3-x^2+2x-2)`

`= 7x^3+x^2-x+5+7x^3+x^2-2x+2`

`=(7x^3+7x^3)+(x^2+x^2)-(x+2x)+(5+2)`

`=14x^3+2x^2-3x+7`

c) `A(x) = P(x)+Q(x)=x+3`

`A(x)=0 <=> x+3=0 <=>x=-3`.

a: A(x)=2x^3+x^2+4x+1

B(x)=-2x^3+x^2+3x+2

b: M(x)=A(x)+B(x)

=2x^3+x^2+4x+1-2x^3+x^2+3x+2

=2x^2+7x+3

c: M(x)=0

=>2x^2+7x+3=0

=>2x^2+6x+x+3=0

=>(x+3)(2x+1)=0

=>x=-3 hoặc x=-1/2

a)\(A\left(x\right)=2x^4-4x^3-x^2+5x+1\)

\(B\left(x\right)=-2x^4+4x^3+x^2-7x+1\)

\(C\left(x\right)=2x^4-4x^3-x^2+5x+1-2x^4+4x^3+x^2-7x+1\)

\(C\left(x\right)=-2x+2\)

\(D\left(x\right)=2x^4-4x^3-x^2+5x+1+2x^4-4x^3-x^2+7x-1\)

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

b)cho C(x)  = 0

\(=>-2x+2=0\Rightarrow-2x=-2\Rightarrow x=1\)

a) A(x)= 2x^4--4x^3--x^2+5x+1
B(x)= 2x^4+4x^3+x^2--7x+1 

A(x)= 2x^4--4x^3--x^2+5x+1

A(x)= 2x^4--4x^3--x^2+5x+1