Question

 tìm x, biết:

 (x + 2)² - (x - 2) (x + 2) = 0

Answer 1

\(\left(x+2\right)^2-\left(x-2\right)\left(x+2\right)=0\)

\(\Leftrightarrow x^2+4x+4-x^2+4=0\)

\(\Leftrightarrow4x+8=0\)

\(\Leftrightarrow4x=0-8\)

\(\Leftrightarrow4x=-8\)

\(\Leftrightarrow x=-8:4\)

\(\Leftrightarrow x=-2\)

Answer 2

\(\left(x+2\right)^2-\left(x+2\right)\left(x-2\right)=0\)

<=> (x+2)(x+2-x+2)=0

<=>(x+2).4=0

<=> x=-2

Answer 3

\(\left(x+2\right)^2-\left(x-2\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left(x^2+4x+4\right)-\left(x^2-2^2\right)=0\)
\(\Leftrightarrow x^2+4x+4-x^2+4=0\)
\(\Leftrightarrow4x+8=0\)

\(\Leftrightarrow4x=-8\)
\(\Leftrightarrow x=-2\)
\(\text{Vậy }x=-2\)