Question

Rút gọn biểu thức A=\(\frac{x^3+2x^2+x}{x^3+x}\)

\(B=\frac{x^2-9}{3-x}\)

Answer 1

\(A=\frac{x^3+2x^2+x}{x^3+x}=\frac{x^3+3x}{x^2+x}=\frac{x^2+3}{x^2+1}\)

\(B=\frac{x^2-9}{3-x}=\frac{x^2-9}{-\left(3-x\right)}=\frac{\left(x-3\right)\left(x+3\right)}{x+3}=x-3\)

Answer 2

Em mới lớp 7 nên rút gọn bừa ạ !!!

\(A=\frac{x^3+2x^2+x}{x^3+x}=\frac{\left(x^3+x\right)+2x^2}{x^3+x}=\frac{x^3+x}{x^3+x}+\frac{2x^2}{x^3+x}=\frac{2x^2}{x^3+x}\)\(=\frac{x^2.x.x}{x.\left(x^2+1\right)}=\frac{x^2.x}{x^2+1}\)

Lm thử sức thôi ạ !!!

Answer 3

\(A=\frac{x^3+2x^2+x}{x^3+x}\)

\(A=\frac{x\left(x^2+2x+1\right)}{\left(x+1\right)\left(x^2+2x+1\right)}\)

\(A=\frac{x}{x+1}\)

\(B=\frac{x^2-9}{3-x}=\frac{\left(x-3\right)\left(x+3\right)}{3-x}\)

\(B=\frac{-\left(x-3\right)\left(x+3\right)}{x-3}\)

\(B=-\left(x+3\right)\)

Answer 4

Lm nốt câu b:

\(B=\frac{x^2-9}{3-x}\Rightarrow-B=\frac{\left(x-3\right)\left(x+3\right)}{x-3}=x+3\)

\(\Rightarrow B=-\left(x+3\right)=3-x\)