2) (6 +y)^2 - 81 = 0;
36+12y+y²-81=0
-45+12y+y²=0
y²+12y-45=0
D=12²-4*1*(-45)=18
y1=-12+18/2=3
y2=-12-18/2=-15
2) (6 +y)^2 - 81 = 0;
36+12y+y²-81=0
-45+12y+y²=0
y²+12y-45=0
D=12²-4*1*(-45)=18
y1=-12+18/2=3
y2=-12-18/2=-15