Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a) Đặt A(x)=0
\(\Leftrightarrow-4x-5=0\)
\(\Leftrightarrow-4x=5\)
hay \(x=-\dfrac{5}{4}\)
b) Đặt B(x)=0
\(\Leftrightarrow3\left(2x-1\right)-2\left(x+1\right)=0\)
\(\Leftrightarrow6x-3-2x-2=0\)
\(\Leftrightarrow4x=5\)
hay \(x=\dfrac{5}{4}\)
a: P(x)=x^3+x^2+x+2
Q(x)=-x^3+x^2-x+1
b: M(x)=P(x)+Q(x)
=x^3+x^2+x+2-x^3+x^2-x+1
=2x^2+3
N(x)=x^3+x^2+x+2+x^3-x^2+x-1
=2x^3+2x+1
c: M(x)=2x^2+3>=3>0 với mọi x
=>M(x) ko có nghiệm
b: 1/2x-4=0
=>1/2x=4
hay x=8
a: x+7=0
=>x=-7
e: 4x2-81=0
=>(2x-9)(2x+9)=0
=>x=9/2 hoặc x=-9/2
g: x2-9x=0
=>x(x-9)=0
=>x=0 hoặc x=9
a: x+7=0
nên x=-7
b: x-4=0
nên x=4
c: -8x+20=0
=>-8x=-20
hay x=5/2
d: x2-100=0
=>(x-10)(x+10)=0
=>x=10 hoặc x=-10
a, \(P\left(x\right)=2x^3-2x+x^2-x^3+3x+2\\ =x^3+x^2+x+2\)
\(Q\left(x\right)=3x^3-4x^2+3x-4x-4x^3+5x^2+1\\ =-x^3+x^2-x+1\)
b) \(M\left(x\right)=x^3+x^2+x+2-x^3+x^2-x+1\\ =2x^2+3\)
\(N\left(x\right)=x^3+x^2+x+2+x^3-x^2+x-1\\ =2x^3+2x+1\)
c, Ta thấy \(2x^2\ge0,3>0\Rightarrow M\left(x\right)>0\)
\(\Rightarrow M\left(x\right)\) không có nghiệm
a: Ta có: \(P\left(x\right)=2x^3-2x+x^2-x^3+3x+2\)
\(=x^3+x^2+x+2\)
Ta có: \(Q\left(x\right)=3x^3-4x^2+3x-4x-4x^3+5x^2+1\)
\(=-x^3-4x^2-x+1\)
b: Ta có: M(x)=P(x)+Q(x)
\(=x^3+x^2+x+2-x^3-4x^2-x+1\)
\(=-3x^2+3\)
Ta có N(x)=P(x)-Q(x)
\(=x^3+x^2+x+2+x^3+4x^2+x-1\)
\(=2x^3+5x^2+2x+1\)
a: P(x)=x^3-x^2+x+2
Q(x)=-x^3+x^2-x+1
b: M(x)=P(x)+Q(x)=x^3-x^2+x+2-x^3+x^2-x+1=3
N(x)=P(x)-Q(x)
=x^3-x^2+x+2+x^3-x^2+x-1
=2x^3-2x^2+2x+1
c: M(x)=3
=>M(x) ko có nghiệm
\(a,P\left(x\right)=2x^3-x+x^2-x^3+3x+5\\ =\left(2x^3-x^3\right)+x^2+\left(-x+3x\right)+5\\ =x^3+x^2+2x+5\\ Q\left(x\right)=3x^3+4x^2+3x-4x^3-5x^2+10\\ =\left(3x^3-4x^3\right)+\left(4x^2-5x^2\right)+3x+10\\ =-x^3-x^2+3x+10\\ b,M\left(x\right)=P\left(x\right)+Q\left(x\right)=x^3+x^2+2x+5-x^3-x^2+3x+10\\ =\left(x^3-x^3\right)+\left(x^2-x^2\right)+\left(2x+3x\right)+\left(5+10\right)=5x+15\\ N\left(x\right)=P\left(x\right)-Q\left(x\right)=x^3+x^2+2x+5-\left(-x^3-x^2+3x+10\right)\\ =x^3+x^2+2x+5+x^3+x^2-3x-10\\ =\left(x^3+x^3\right)+\left(x^2+x^2\right)+\left(2x-3x\right)+\left(5-10\right)\\ =2x^3+2x^2-x-5\)
`a,P(x)= 2x^3 -x+x^2 -x^3 +3x+5`
`= (2x^3 -x^3)+x^2+(-x+3x) +5`
`= x^3 +x^2 + 2x+5`
`Q(x)=3x^3 +4x^2+3x-4x^3-5x^2+10`
`= (3x^3-4x^3)+(4x^2-5x^2)+3x+10`
`= -x^3 -x^2+3x+10`
`b,M(x)=P(x)+Q(x)`
`->M(x)=(x^3 +x^2 + 2x+5)+(-x^3 -x^2+3x+10)`
`=x^3 +x^2 + 2x+5+(-x^3) -x^2+3x+10`
`=(x^3 -x^3)+(x^2 -x^2)+(2x+3x)+(5+10)`
`= 5x+15`
`N(x)=P(x)-Q(x)`
`->N(x)=(x^3 +x^2 + 2x+5)-(-x^3 -x^2+3x+10)`
`=x^3 +x^2 + 2x+5-x^3 +x^2-3x-10`
`=(x^3-x^3)+(x^2+x^2)+(2x-3x)+(5-10)`
`=2x^2 -x-5`
