a: \(C\left(x\right)=A\left(x\right)+B\left(x\right)\)

\(=3x^4-4x^3+5x^2-4x-3-3x^4+4x^3-5x^2+2x+6\)

=-2x+3

b: Đặt C(x)=0

=>-2x+3=0

hay x=3/2

Chọn B

Ta có A(x) + B(x) = (3x4 - 4x3+ 5x2 - 3-4x) + (-3x4+ 4x3 - 5x2+ 6 + 2x) = -2x + 3.

Ta có : 

\(3x^4-4x^3+5x^2-3-4x-3x^4+4x^3-5x^2+6+2x\)

\(=3-2x\)hay \(-2x+3\)

Suy ra : Ta chọn B 

3x⁴ - 4x³ + 5x² - 3 - 4x - 3x⁴ + 4x³ - 5x² + 6 + 2x

= 3 - 2x

CHON B

Trước hết, ta rút gọn các đa thức:

- Q(x) = 4x3 – 2x + 5x2 - 2x3 + 1 - 2x3

Q(x) = (4x3- 2x3- 2x3) – 2x + 5x2 + 1

Q(x) = 0 – 2x + 5x2 + 1

Q(x) = – 2x + 5x2 + 1

- R(x) = - x2 + 2x4 + 2x - 3x4 – 10 + x4

R(x) = - x2 + (2x4- 3x4+ x4) + 2x – 10

R(x) = - x2 + 0 + 2x – 10

R(x) = - x2 + 2x – 10

Sắp xếp các hạng tử của đa thức sau theo lũy thừa giảm dần của biến ta có:

Q(x) = 5x2 – 2x + 1

R(x) = - x2 + 2x – 10

`a)`

`Q(x)=-2x^{3}+7x^{2}-9x+12`

`b)`

`P(x)+Q(x)=4x^{3}-7x^{2}+3x-12-2x^{3}+7x^{2}-9x+12`

`=2x^{3}-6x`

``

`2P(x)-Q(x)=8x^{3}-14x^{2}+6x-24-2x^{3}+7x^{2}-9x+12`

`=6x^{3}-7x^{2}-3x-12`

`c)`

`P(x)+Q(x)=0`

`->2x^{3}-6x=0`

`->2x(x^{2}-3)=0`

`->x=0` hoặc `x^{2}-3=0`

`->x=0` hoặc `x=+-\sqrt{3}`

a) \(Q=-2x^3+2x^2+12+5x^2-9x=-2x^3+7x^2-9x+12\)

b) \(P+Q=4x^3-7x^2+3x-12-2x^3+7x^2-9x+12=2x^3-6x\)

\(2P-Q=2\left(4x^3-7x^2+3x-12\right)-\left(-2x^3+7x^2-9x+12\right)=8x^3-14x^2+6x-24+2x^3-7x^2+9x-12=10x^3-21x^2+15x-36\)c) \(P+Q=2x^3-6x=0\)

\(\Leftrightarrow2x\left(x^2-3\right)=0\Leftrightarrow\left[{}\begin{matrix}2x=0\\x^2-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\pm\sqrt{3}\end{matrix}\right.\)

a: Ta có: \(Q=-2x^3+2x^2+12+5x^2-9x\)

\(=-2x^3+7x^2-9x+12\)

b: Ta có: P+Q

\(=4x^3-7x^2+3x-12-2x^3+7x^2-9x+12\)

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

Ta có: 2P+Q

\(=8x^3-14x^2+6x-24-2x^3+7x^2-9x+12\)

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

bó tay . com . vn

a: \(P\left(x\right)=4x^3+x^2-2x+7\)

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

b: \(M\left(x\right)=4x^3+x^2-2x+7-4x^3-x^2+4x-3=2x+4\)

\(N\left(x\right)=8x^3+2x^2-6x+10\)

c: Đặt M(x)=0

=>2x+4=0

hay x=-2

\(a,Q_{\left(x\right)}=-4x^3+2x-2+2x-x^2-1\\ Q_{\left(x\right)}=-4x^3-x^2+4x-3\\ P_{\left(x\right)}=4x^3-3x+x^2+7+x\\ P_{\left(x\right)}=4x^3+x^2-2x+7\)

\(b,M_{\left(x\right)}=P_{\left(x\right)}+Q_{\left(x\right)}\\ M_{\left(x\right)}=4x^3+x^2-2x+7-4x^3-x^2+4x-3\\ M_{\left(x\right)}=2x+4\)

\(N_{\left(x\right)}=4x^3+x^2-2x+7+4x^2+x^2-4x+3\\ N_{\left(x\right)}=8x^3+2x^2-6x+10\)

\(c,M_{\left(x\right)}=0\\ \Rightarrow2x+4=0\\ \Rightarrow2x=-4\\ \Rightarrow x=-2\)

a)\(P\left(x\right)=4x^3+x^2-2x+7\)

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

b)\(M\left(x\right)=4x^3+x^2-2x+7-4x^3-x^2-4x+3\)

\(M\left(x\right)=-6x+10\)

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

\(N\left(x\right)=8x^3+2x^2+2x+4\)

c) cho M(x) = 0

\(=>-6x+10=0\)

\(-6x=-10\Rightarrow x=-\dfrac{10}{-6}=\dfrac{5}{3}\)

A(x)=(7x²-5x²-2x²)-(6x³-10x³)+2x-12

A(x)=-4x³+2x-12

Sắp xếp:-4x³+2x-12

\(A\left(x\right)=\left(7x^2-5x^2-2x^2\right)-\left(6x^3-10x^3\right)+2x-12\)

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

Sắp xếp:\(-4x^3+2x-12\)

\(a,f\left(x\right)+g\left(x\right)=5x^2-2x+5+5x^2-6x-\dfrac{1}{3}\\ =10x^2-8x+\dfrac{14}{3}\\ b,f\left(x\right)-g\left(x\right)=5x^2-2x+5-5x^2+6x+\dfrac{1}{3}\\ =4x+\dfrac{16}{3}\\ c,f\left(x\right)-g\left(x\right)=4x+\dfrac{16}{3}=0\\ \Leftrightarrow4x=-\dfrac{16}{3}\Leftrightarrow x=-\dfrac{4}{3}\)