Question

1.Phân tích đa thức sau thành nhân tử:

a.x²-x-y²-y

b.25(x-y)²-16(x+y)²

c.x⁴-8+2x²

d.x³+2x²y+xy²-9x

2.Tìm x, biết:

a.x²-25=0

b.5x²-10x=0

Answer 1

\(2.\)

\(a.\)

\(x^2-25=0\)

\(\Rightarrow x^2-5^2=0\)

\(\Rightarrow\left(x-5\right)\left(x+5\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-5=0\\x+5=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=5\\x=-5\end{matrix}\right.\)

\(b.\)

\(5x^2-10x=0\)

\(\Rightarrow5x\left(x-10\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}5x=0\\x-10=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x=10\end{matrix}\right.\)