Question

1,

a,(4x³y²-6x²y²+x²y):(-2xy)

b,(x⁴-3x+x³-2x²+1):(x²-x+1)

c,(x⁷+x⁵+1):(x²-x+1)

2,tìm a,b,để 

(x⁴+3x³+ax²-2x+b) chia hết (x²-x+1)
3, tìm GTNN 

A=x(x-3)

B=2x²-x+4

giúp mình có kq trcs sáng t5 với ạ

Answer 1

Câu 3:

a: \(A=x^2-3x+\dfrac{9}{4}-\dfrac{9}{4}=\left(x-\dfrac{3}{2}\right)^2-\dfrac{9}{4}>=-\dfrac{9}{4}\)

Dấu '=' xảy ra khi x=3/2

b: \(B=2\left(x^2-\dfrac{1}{2}x+2\right)\)

\(=2\left(x^2-2\cdot x\cdot\dfrac{1}{4}+\dfrac{1}{16}+\dfrac{15}{16}\right)\)

\(=2\left(x-\dfrac{1}{4}\right)^2+\dfrac{15}{8}>=\dfrac{15}{8}\)

Dấu '=' xảy ra khi x=1/4

Answer 2

2) 

Để \(x^4+3x^2+ax^2-2x+b\) chia hết cho \(x^2-x+1\) thì:

\(\left\{{}\begin{matrix}a-9=0\\a+b-3=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=9\\b=-6\end{matrix}\right.\)