Question

(x-4)(x+4)-2(3x-2)=(x-4)^2

Answer 1

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

\(\Leftrightarrow x^2-16-6x+4=x^2-8x+16\)

\(\Leftrightarrow x^2-6x-12-x^2+8x-16=0\)

\(\Leftrightarrow2x-28=0\)

\(\Leftrightarrow2x=28\)

hay x=14

Vậy: S={14}

Answer 2

(x-4).(x+4)-2(3x-2)=(x-4)²

⇔x² +4x-4x-16-6x+4=x²-8x+16

⇔x²-12-6x=x²-8x+16

⇔x²-x²-6x+8x=16+12

⇔2x=28

⇔x=14

 

Answer 3

\(\left(x-4\right)\left(x+4\right)-2\left(3x-2\right)=\left(x-4\right)^2\\ \Leftrightarrow x^2-16-6x+4=x^2-4x+4\\\Leftrightarrow 2x=-16\\ \Leftrightarrow x=-8\\\)