Question

Answer 1

\(\dfrac{8x^2-2}{4x^2y}-\dfrac{4x^2-2}{4x^2y}\)=\(\dfrac{8x^2-2-4x^2+2}{4x^2y}=\dfrac{4x^2}{4x^2y}=\dfrac{1}{y}\)

=>Không có câu nào đúng cả :)

Answer 2

câu D

Answer 3

\(\dfrac{8x^2-2}{4x^2y}-\dfrac{4x^2-2}{4x^2y}=\dfrac{2\left(2x-1\right)\left(2x+1\right)}{4x^2y}-\dfrac{4x^2-2}{4x^2y}=\dfrac{2\left(2x-1\right)\left(2x+1\right)}{2x^2y}-\dfrac{2\left(2x^2-1\right)}{4x^2y}\)

\(=\dfrac{\left(2x-1\right)\left(2x+1\right)}{2x^2y}-\dfrac{2x^2-1}{2^2y}=\dfrac{\left(2x-1\right)\left(2x+1\right)-\left(2x^2-1\right)}{2x^2y}=\dfrac{2x^2}{2x^2y^{ }}\)

\(=\dfrac{1}{y}\)

Có cái nào đúng đâu trời ơi