Câu hỏi của Ánh Thảo

Question

cho đa thức P(x)=x5 -2x4 -7 + x

tìm các đa thức Q(x),R(x) sao cho

a) P(x) +Q(x)=16x6 - 3x4 + 5

b) P(x)-R(x)=x4

giúp mik với mik đag cần gấp

Komorebi · Accepted Answer

a) $P\left(x\right)+Q\left(x\right)=16x^6-3x^4+5$

$\Rightarrow\text{​​}$$x^5-2x^4-7+x+Q\left(x\right)=16x^6-3x^4+5$

$\Rightarrow Q\left(x\right)=x^5-2x^4-7+x-\left(16x^6-3x^4+5\right)$

$\Rightarrow Q\left(x\right)=x^5-2x^4-7+x-16x^6+3x^4-5$

$\Rightarrow Q\left(x\right)=-16x^6+x^5+x^4+x-12$

b) $P\left(x\right)-R\left(x\right)=x^4$

$\Rightarrow x^5-2x^4-7+x-R\left(x\right)=x^4$

$\Rightarrow R\left(x\right)=x^5-2x^4-7+x-x^4$

$\Rightarrow R\left(x\right)=x^5-3x^4+x-7$Câu trả lời: a) $P\left(x\right)+Q\left(x\right)=16x^6-3x^4+5$

$\Rightarrow\text{​​}$$x^5-2x^4-7+x+Q\left(x\right)=16x^6-3x^4+5$

$\Rightarrow Q\left(x\right)=x^5-2x^4-7+x-\left(16x^6-3x^4+5\right)$

$\Rightarrow Q\left(x\right)=x^5-2x^4-7+x-16x^6+3x^4-5$

$\Rightarrow Q\left(x\right)=-16x^6+x^5+x^4+x-12$

b) $P\left(x\right)-R\left(x\right)=x^4$

$\Rightarrow x^5-2x^4-7+x-R\left(x\right)=x^4$

$\Rightarrow R\left(x\right)=x^5-2x^4-7+x-x^4$

$\Rightarrow R\left(x\right)=x^5-3x^4+x-7$

Vũ Thùy Linh · Answer

a) P(x)+Q(x)=16x6−3x4+5

P(x)+Q(x)=16x6−3x4+5

⇒x5−2x4−7+x+Q(x)=16x6−3x4+5x5−2x4−7+x+Q(x)=16x6−3x4+5

⇒Q(x)=x5−2x4−7+x−(16x6−3x4+5)⇒Q(x)=x5−2x4−7+x−(16x6−3x4+5)

⇒Q(x)=x5−2x4−7+x−16x6+3x4−5⇒Q(x)=x5−2x4−7+x−16x6+3x4−5

⇒Q(x)=−16x6+x5+x4+x−12⇒Q(x)=−16x6+x5+x4+x−12

b) P(x)−R(x)=x4P(x)−R(x)=x4

⇒x5−2x4−7+x−R(x)=x4⇒x5−2x4−7+x−R(x)=x4

⇒R(x)=x5−2x4−7+x−x4⇒R(x)=x5−2x4−7+x−x4

⇒R(x)=x5−3x4+x−7Câu trả lời: a) P(x)+Q(x)=16x6−3x4+5