giúp với :(
Q(x)=x4+4x3+2x2-4x+1 Tính:Q=-2;Q=-1
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`Q(-2)=(-2)^4+4*(-2)^3+2*(-2)^2-4*(-2)+1`
`= 16+4*(-8)+2*4+8+1`
`= 16-32+8+8+1`
`= -16+8+8+1`
`= -8+8+1=1`
`Q(1)=1^4+4*1^3+2*1^2-4*1+1`
`= 1+4+2-4+1`
`= 2+2+4-4=4`
Q(-2) = (-2)⁴ + 4.(-2)³ + 2.(-2)² - 4.(-2) + 1
= 16 - 32 + 8 + 8 + 1
= 1
--------------------
Q(1) = 1⁴ + 4.1³ + 2.1² - 4.1 + 1
= 1 + 4 + 2 - 4 + 1
= 4
\(P\left(-1\right)=\left(-1\right)^4+2.\left(-1\right)^2+1=4\\ P\left(1\right)=1^4+2.1^2+1=4\)
\(P\left(-1\right)=\left(-1\right)^4+2\cdot\left(-1\right)^2+1=4\)
\(P\left(1\right)=P\left(-1\right)=4\)
\(Q\left(2\right)=2^4+4\cdot2^3+2\cdot2^2-4\cdot2+1=49\)
\(Q\left(1\right)=1^4+4\cdot1^3+2\cdot1^2-4\cdot1+1=4\)
Cho các đa thức: P(x)=x4+2x2+1 và Q(x)=x4+4x3+2x2-4x+1
Tính P(x)-Q(x) các bn giải giùm mik nhé.......
c) Ta có: \(C=4x^2+y^2-4xy+8x-4y+4\)
\(=\left(2x-y\right)^2+2\cdot\left(2x-y\right)\cdot2+2^2\)
\(=\left(2x-y+2\right)^2\)
a: \(x^4+2x^3+3x^2+2x+1\)
\(=x^4+x^3+x^2+x^3+x^2+x+x^2+x+1\)
\(=x^2\left(x^2+x+1\right)+x\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2+x+1\right)=\left(x^2+x+1\right)^2\)
b: \(x^4-4x^3+2x^2+4x+1\)
\(=x^4-2x^3-x^2-2x^3+4x^2+2x-x^2+2x+1\)
\(=x^2\left(x^2-2x-1\right)-2x\left(x^2-2x-1\right)-\left(x^2-2x-1\right)\)
\(=\left(x^2-2x-1\right)\left(x^2-2x-1\right)=\left(x^2-2x-1\right)^2\)
c: \(x^4+x^3+2x^2+2x+4\)
\(=x^4-x^3+2x^2+2x^3-2x^2+4x+2x^2-2x+4\)
\(=x^2\left(x^2-x+2\right)+2x\left(x^2-x+2\right)+2\left(x^2-x+2\right)\)
\(=\left(x^2-x+2\right)\left(x^2+2x+2\right)\)
a) \(P\left(x\right)=3x^3-x^2-2x^4+3+2x^3+x+3x^4-x^2-2x^4+3+2x^3+x+3x^4\)
\(=2x^4+7x^3-2x^2+2x+6\)
\(Q\left(x\right)=-x^4+x^2-4x^3-2+2x^2-x-x^3-x^4+x^2-4x^3-2+2x^2-x-x^3\)
\(=-2x^4-10x^3+6x^2-2x-4\)
b) \(P\left(x\right)+Q\left(x\right)=2x^4+7x^3-2x^2+2x+6-2x^4-10x^3+6x^2-2x-4\)
\(=-3x^3+4x^2+2\)
Ta có
P ( x ) = 2 x 3 − 3 x + x 5 − 4 x 3 + 4 x − x 5 + x 2 − 2 = x 5 − x 5 + 2 x 3 − 4 x 3 + x 2 + ( 4 x − 3 x ) − 2 = − 2 x 3 + x 2 + x − 2 Và Q ( x ) = x 3 − 2 x 2 + 3 x + 1 + 2 x 2
= x 3 + - 2 x 2 + 2 x 2 + 3 x + 1 = x 3 + 3 x + 1
Khi đó
P ( x ) − Q ( x ) = − 2 x 3 + x 2 + x − 2 − x 3 + 3 x + 1 = − 2 x 3 + x 2 + x − 2 − x 3 − 3 x − 1 = − 2 x 3 − x 3 + x 2 + ( x − 3 x ) − 2 − 1 = − 3 x 3 + x 2 − 2 x − 3
Chọn đáp án B
Ta có
P ( x ) = 2 x 3 − 3 x + x 5 − 4 x 3 + 4 x − x 5 + x 2 − 2 = x 5 − x 5 + 2 x 3 − 4 x 3 + x 2 + ( 4 x − 3 x ) − 2 = − 2 x 3 + x 2 + x − 2 Và Q ( x ) = x 3 − 2 x 2 + 3 x + 1 + 2 x 2 = x 3 + − 2 x 2 + 2 x 2 + 3 x + 1 = x 3 + 3 x + 1
Khi đó
M ( x ) = P ( x ) + Q ( x ) = − 2 x 3 + x 2 + x − 2 + x 3 + 3 x + 1 = − 2 x 3 + x 2 + x − 2 + x 3 + 3 x + 1 = − 2 x 3 + x 3 + x 2 + ( x + 3 x ) − 2 + 1 = − x 3 + x 2 + 4 x − 1
Bậc của M ( x ) = - x 3 + x 2 + 4 x - 1 l à 3
Chọn đáp án C
\(Q\left(x\right)=x^4+4x^3+2x^2-4x+1\)
\(\Rightarrow Q\left(-2\right)=\left(-2\right)^4+4\cdot\left(-2\right)^3+2\cdot\left(-2\right)^2-4\cdot\left(-2\right)+1=1\)
\(Q\left(-1\right)=\left(-1\right)^4+4\cdot\left(-1\right)^3+2\cdot\left(-1\right)^2-4\cdot\left(-1\right)+1=4\)