= 1/2x-( 1/x+y)((x+y)*(x-y)+x+y/2x)

= 1/2x- ( x-y- 1/2x)

= 1/x -x +y Do it yourself.

2:a？ + b？ -6ab = 0. Add 2ab to both sides to get the square of a+b =8ab, and subtract 2ab to get the square of a-b =4ab.

The value obtained by dividing the two formulas is 2.

3. It is known that both sides of the equation are multiplied by ab at the same time, and a+b=4ab is substituted into the required score, and the result is 1.

4: both sides of the equation are divided by x at the same time, 5x-3-5/x = 0 5x-5/x = 3x-1/x = 3/5, and both sides are squared at the same time. -2+ 1/x？ =9/25

Get x? + 1/x？ =9/25+2=59/25

5: Substitute the known available x=- 1 into the required score to get 1/3.

Learning to use some jobs, these are very simple topics.