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\(x^4+2010x^2+2009x+2010\)
\(=x^4-x+\left(2010x^2+2010x+2010\right)\)
\(=x\left(x^3-1\right)+2010\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+2010\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x\left(x-1\right)+2010\right]=\left(x^2+x+1\right)\left(x^2-x+2010\right)\)
a)
x4+2010x2+2009x+2010
= (x4-x)+(2010x2+2010x+2010)
= x(x3-1)+2010(x2+x+1)
= x(x-1)(x2+x+1) +2010(x2+x+1)
= (x2+x+1)(x2-x+2010)
b)
x3-x2-5x+21
= x3+3x2-4x2-12x+7x+21
= x2(x+3)-4x(x+3)+7(x+3)
= (x+3)(x2-4x+7)
gọi đa thức phân tích là (x2+ax+b)(x2+cx+d)
(x2+ax+b)(x2+cx+d)=x4+(c+a)x3+x2(d+ac+b)+x(ad+bc)+bd
đồng nhất hệ số ta có a+c = 0
d+b+ac=2009
ad+bc = 2008
bd = 2009
=> a = 1 ; b =1 ; c = -1 ; d =2009
vậy đa thức phân tích là (x^2+x+1)(x^2-x+2009)
bạn phân tích ra xem có đúng ko nha
x4+2009x2+2008x+2009
=(x4-x)+(2009x2+2009x+2009)
=x(x3-1)+2009(x2+x+1)
=x(x-1)(x2+x+1)+2009(x2+x+1)
=(x2+x+1)(x(x-1)+2009)
=(x2+x+1)(x2-x+2009)
k mình nha, chúc bạn học giỏi!!!
cách 1 dùng hệ số bất định
có hệ
a+c=0
ac+b+d= 2009
ad+bc=2008
bd=2009
Ta tìm được a=1,b=1,d=2009,c=-1
=> (x^2+x+1)(x^2-x+2009)=0
Cách 2:
có (x^2+m)^2 =2mx^2+m^2 +2009x^2+2009x+2009=x^2(2009+2m) +2008x +2009+m^2
xét \delta thấy vô nghiệm => PT vô nghiệm
x4+2011x2+2010x+2011
=(x4+x3+x2)+(2011x2+2011x+2011)-(x3+x2+x)
=x2(x2+x+1)+2011(x2+x+1)-x(x2+x+1)
=(x2+x+1)(x2+2011-x)
x4+2011x2+2010x+2011=x4-x+2011x2+2011x+2011
=x(x3-1)+2011(x2+x+1)
=x(x- 1)(x2+x+1)+2011(x2+x+1)
=(x2+x+1)[x(x-1)+2011]
=(x2+x+1)(x2-x+2011)
a.\(\left(x+y+z\right)^3-x^3-y^3-z^3\)
\(=\left[\left(x+y\right)^3+z^3\right]-a^3-b^3-c^3\)
\(=\left(x+y\right)^3+z^3+3z\left(x+y\right)\left(x+y+z\right)-x^3-y^3-z^3\)
\(=x^3+y^3+3xy\left(x+y\right)+z^3+3z\left(x+y\right)\left(x+y+z\right)-x^3-y^3-z^3\)
\(=3\left(x+y\right)\left(xy+xz+yz+z^2\right)\)
\(=3\left(x+y\right)\left[x\left(y+z\right)+z\left(y+z\right)\right]\)
\(=3\left(x+y\right)\left(y+z\right)\left(z+x\right)\)
b.\(x^4+2010x^2+2009x+2010\)
\(=\left(x^4-x\right)+\left(2010x^2+2010x+2010\right)\)
=\(x\left(x-1\right)\left(x^2+x+1\right)+2010\left(x^2+x+1\right)\)
=\(\left(x^2+x+1\right)\left(x^2-x+2010\right)\)
sửa đề:\(\left(x+y+z\right)^3-x^3-y^3-z^3\)
giải:
\(\left(x+y+z\right)^3-x^3-y^3-z^3=x^3+y^3+z^3+3\left(x+y\right)\left(y+z\right)\left(z+x\right)-x^3-y^3-z^3\\ =3\left(x+y\right)\left(y+z\right)\left(z+x\right)\)
b,W = \(x^4+x^2+1+2009x^2+2009x+2009\)
\(=\left(x^4+2x^2+1\right)-x^2+2009\left(x^2+x+1\right)\)
\(=\left(x^2+1\right)^2-x^2+2009\left(x^2+x+1\right)\)
\(=\left(x^2+1-x\right)\left(x^2+1+x\right)+2009\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+2010\right)\)
\(x^4+2010x^2+2009x+2010\)
\(=\left(x^4-x\right)+2010\left(x^2+x+1\right)\)
\(=x\left(x^3-1\right)+2010\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+2010\left(x^2+x+1\right)\)
\(=\left(x^2-x+2010\right)\left(x^2+x+1\right)\)