2)[(x-y)(x+y)]? (x? +y? )? =(x? -Really? )? (x? +y? )? =(x^4-y^4)? =x^8-2x^4y^4+y^8
3)x? +y? =(x-y)? +2xy=8 1+2*5=9 1 (x+y)? =x? +y? +2xy = 9 1+ 10 = 10 1
4)x? -2x+y? +6y+ 1+9=0
(x? -2x+ 1)+(y? +6y+9)=0
(x— 1)? +(y+3)? =0
x- 1=0,y+3=0
x= 1.y=-3
5)x? + 1/x? =(x+ 1/x)? -2=4? -2= 14