Question 48473
ok, solve means "where does the curve cross the x-axis?" ie this is where y=0.


So {{{ x^2+y^2=20 }}} becomes
{{{ x^2+(0)^2=20 }}}
{{{ x^2=20 }}}
{{{ x=sqrt(20) }}} or {{{ x=-sqrt(20) }}}


which are the 2 answers. However, we usually try to simplify a square root if possible. Here we can:
{{{ x=sqrt(20) }}} or {{{ x=-sqrt(20) }}}
{{{ x=sqrt(4*5) }}} or {{{ x=-sqrt(4*5) }}}
{{{ x=sqrt(4)sqrt(5) }}} or {{{ x=-sqrt(4)sqrt(5) }}}
{{{ x=2sqrt(5) }}} or {{{ x=-2sqrt(5) }}}


jon