Question 587667
1. {{{sqrt(y+15)-sqrt(y-15)=1}}}
Squaring both sides gives {{{y + 15 + y - 15 - 2*sqrt((y+15)(y-15)) = 1}}}
Simplifiy and isolate the square root on the LHS:
{{{sqrt((y+15)(y-15)) = y - 1/2}}}
Now square both sides again:
{{{(y+15)(y-15) = y^2 - y + 1/4}}}
{{{y^2 - 225 = y^2 -y + 1/4}}}
Simplify:
y = 225 1/4