Question

Answer 1

a: ĐKXĐ: x∉{0;-1}

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

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

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

b: Thay x=4 vào A, ta được:

\(A=\frac{4^2+4+1}{4}=\frac{16+5}{4}=\frac{21}{4}\)

c: A=3

=>\(x^2+x+1=3x\)

=>\(x^2-2x+1=0\)

=>\(\left(x-1\right)^2=0\)

=>x-1=0

=>x=1(nhận)