a, \(P\left(x\right)=5x^5-4x^2+7x+1;Q\left(x\right)=5x^5-4x^2+3x+8\)

b, \(P\left(x\right)+Q\left(x\right)=10x^5-8x^2+10x+9\)

c, \(P\left(x\right)=Q\left(x\right)\Rightarrow7x+1=3x+8\Leftrightarrow4x=7\Leftrightarrow x=\dfrac{7}{4}\)

a/ \(P\left(x\right)=8x^5+7x-6x^2-3x^5+2x^2+1\)

\(=8x^5-3x^5-6x^2+2x^2+7x+1\)

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

\(Q\left(x\right)=4x^5+3x-2x^2+x^5-2x^2+8\)

\(=4x^5+x^5-2x^2-2x^2+3x+8\)

\(=5x^5-4x^2+3x+8\)

b/ \(P\left(x\right)=5x^5-4x^2+7x+1\)

+  \(Q\left(x\right)=5x^5-4x^2+3x+8\)

____________________________

\(P\left(x\right)+Q\left(x\right)=10x^5-8x^2+10x+9\)

c/ \(P\left(x\right)=Q\left(x\right)\)

\(\Rightarrow5x^5-4x^2+7x+1=5x^5-4x^2+3x+8\)

\(\Rightarrow7x+1=3x+8\)

\(\Rightarrow4x-7=0\)

\(\Rightarrow x=\dfrac{7}{4}\)

a) P(x) = 5x⁵ - 4x² + 7x + 15

Q(x) = 5x⁵ - 4x² + 3x + 8

b) Có: P(x) - Q(x) = 4x + 7

P(x) - Q(x) = 0 <=> x = \(-\dfrac{-7}{4}\)

`a,```P(x) = 8x^5 +7x -6x^2 -3x^5 +2x^2+15`

`= (8x^5 -3x^5 ) +(-6x^2+2x^2) +7x+15`

`=5x^5 -4x^2 +7x+15`

`Q(x) =4x^5 +3x-2x^2 +x^5 -2x^2+8`

`=(4x^5+x^5) +(-2x^2  -2x^2)+3x+8`

`= 5x^5 - 4x^2 +3x+8`

`b, P(x) -Q(x)=(5x^5 -4x^2 +7x+15)-(5x^5 - 4x^2 +3x+8)`

`= 5x^5 -4x^2 +7x+15-5x^5 +4x^2 -3x-8`

`= (5x^5-5x^5)+(-4x^2+4x^2) +(7x-3x)+(15-8)`

`= 0 + 0 +4x + 7`

`=4x+7`

`@`\(P\left(x\right)=3x^5-5x^2+x^4-2x-x^5+3x^4-x^2+x+1\)

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

\(P\left(x\right)=2x^5+x^4-6x^2-x+1\)

`@`\(Q\left(x\right)=-5-3x^5-2x+3x^2-x^5+2x-3x^3-3x^4\)

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

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

`@`\(P\left(x\right)+Q\left(x\right)=\left(2x^5+x^4-6x^2-x+1\right)+\left(-4x^5-3x^4-3x^3+3x^2-5\right)\)

                      \(=-2x^5-2x^4-3x^3-3x^2-x-4\)

j vậy

vừa hỏi vừa trả lời là sao

a: \(A=-5x^3+9x^3-2x^2-2x^2+x-x+1\)

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

\(B=-4x^3+2x^3-2x^2+2x^2+6x-9x-2\)

\(=-2x^3-3x-2\)

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

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

\(=4x^3-4x^2+1-2x^3-3x-2+x^3-6x^2+2x-4\)

\(=3x^3-10x^2-x-4\)

a: \(M=3x^5y^3-3x^5y^3-4x^4y^3+2x^4y^3+7xy^2=-2x^4y^3+7xy^2\)

b: \(P\left(x\right)=2x^3-2x+x^2-x^3+3x+2=x^3+x^2+x+2\)

c: \(M\left(x\right)=-3x^4y^3+10+xy\)

\(a)M=3x^5y^3-4x^4y^3+2x^4y^3+7xy^2-3x^5y^3\)

\(M=\left(3x^5y^3-3x^5y^3\right)+\left(-4x^4y^3+2x^4y^3\right)+7xy^2\)

\(M=-2x^4y^3+7xy^2\)

\(\text{Bậc là:}7\)

\(b)P\left(x\right)=2x^3-2x+x^2-x^3+3x+2\)

\(P\left(x\right)=\left(2x^3-x^3\right)+\left(-2x+3x\right)+x^2+2\)

\(P\left(x\right)=x^3+x+x^2+2\)

\(P\left(x\right)=x^3+x^2+x+2\)

\(\text{Bậc là:}3\)

\(M=\left(6x^6y-6x^6y\right)+\left(x^4y^3-4x^4y^3\right)+10+xy\)

\(M=-3x^4y^3+10+xy\)

\(\text{Bậc là:}7\)

ta có :

\(M=3x^5y^3-4x^4y^3+2x^4y^3+7xy^2-3x^5y^3=-2x^4y^3+7xy^2\)

Bậc của M là \(4+3=7\)

tại x=1 và y=-1 ta có \(M=-2.1^4.\left(-1\right)^3+7.1.\left(-1\right)^2=2+7=9\)