Question 165943
#1) Almost, {{{sqrt(9)=3}}}
{{{y^2 = -9}}}
{{{y=0 +- sqrt(-9)}}}
{{{y=0 +- 3*sqrt(-1)}}}
{{{y=0 +- 3i}}}
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#2) Correct
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#3)You're on the right track.
Distribute on the left hand side.

{{{(y+1)(y-1) (2/(y+1) + 1/(y-1)) = 1((y+1)(y-1))}}}
{{{ ((2*cross((y+1))(y-1))/cross((y+1)) + ((y+1)cross((y-1)))/cross((y-1))) = y^2-1}}}
{{{ 2*(y-1) + (y+1) = y^2-1}}}

{{{ 2y-2+y+1 = y^2-1}}}
{{{ 3y-1 = y^2-1}}}

{{{ 3y=y^2}}}
You can factor out a y but before you do that remember that y=0 is a solution.
{{{y=3}}}
Check the answer.
{{{2/(y+1)+1/(y-1)=1}}}
{{{2/(0+1)+1/(0-1)=1}}}
{{{2-1=1}}}
True.
{{{2/(y+1)+1/(y-1)=1}}}
{{{2/(3+1)+1/(3-1)=1}}}
{{{2/4+1/2=1}}}
True.
y=0, y=3.