Question

\(x-4+\sqrt{x^2-8x+16}\) với x nhỏ 4

 

Answer 1

\(x-4+\sqrt{x^2-8x+16}\left(1\right)=x-4+\sqrt{\left(x-4\right)^2}=x-4+\left|x-4\right|\)

TH1: x<4

\(\left(1\right)=x-4-x+4=0\)

TH2: \(x\ge4\)

\(\left(1\right)=x-4+x-4=2x-8\)

 

Answer 2

\(x-4+\sqrt{x^2-8x+16}\)

\(=x-4+\left|x-4\right|\)

\(=x-4+4-x\)

=0