1)cm :
x|/y -y|/x |/x|/y ( |/x-|/y)
____________=_________________=|/xy (đpcm)
|/x-|/y |/x- |/y
2)cm :
1. 1. |/a+1
(______+________):____________
a-|/a |/a-1. a+1-2|/a
1. 1. |/a +1
=(___________+________):____________
|/a(|/a-1). |/a-1 (|/a+1)²
1+|/a 1. 1. |/a-1
=____________:___________=_____________=________
|/a (|/a-1) |/a+1 |/a (|/a -1). |/a
3)
x|/x +y|/y. x|/x +y|/y - (|/x-|/y)² (|/x+|/y)
_______________-(|/x-|/y)² =________________________
|/x+|/y |/x+|/y
x|/x +y|/y -(x -2|/xy +y )(|/x +|/y)
=___________________________________
|/x+|/y
x|/x +y|/y -x|/x -x|/y +2x|/y +2y|/x -y|/x -y|/y
= ______________________________________________
|/x+|/y
-x|/y -y|/x +2 x|/y +2y|/x
=___________________________
|/x+|/y
=|/xy (đpcm).
d)
1-a|/a ( 1-|/a )²
__________+|/a. ( _________)
1-|/a ( 1-a )²
1-|/a³ ( 1-|/a)²
=____________+|/a .(_________)
1-|/a ( 1-a)²
=1(đpcm)