Question

Dùng định nghĩa chứng minh hai phân thức bằng nhau chứng tỏ rằng:

\(\dfrac{x^3+8}{x^2-2x+4}\)= x+2

Answer 1

Ta có: \(\dfrac{x^3+8}{x^2-2x+4}=x+2\)

\(\Rightarrow\left(x^3+8\right)=\left(x^2-2.x+2^2\right)\left(x+2\right)\)

\(\Rightarrow x^3+8=x^3+8\)

\(\rightarrowđpcm.\)

Answer 2

Ta có : \(\dfrac{x^3+2^3}{x^2-2x+4}=\dfrac{\left(x+2\right)\left(x^2-2x+4\right)}{x^2-2x+4}=x+2\left(đpcm\right)\)

Answer 3

\(\dfrac{x^3+8}{x^2-2x+4}=x+2\)

\(\rightarrow\left(x^2-2x+4\right)\left(x+2\right)=x^3+8\)

\(\rightarrow x^3+8=x^3+8\left(đpcm\right)\)