Question 718182
It can intersect the y-axis either:
(a) once
(b) not at all
If it intersected more than once, that would violate the 
definition of a function, which  needs 1 unique value of
{{{ y }}} for each {{{ x }}}
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In this case, set {{{ x = 0 }}} to find y-crossing
{{{ y = 5x^2 - 1 }}}
{{{ y = 5*0 - 1 }}}
{{{ y = -1 }}}
so, the y-crossing is at (0,-1)
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The x-crossing(s) is where {{{ y = 0 }}}, and there can be
(a) none
(b) one
(c) two
for a 2nd degree equation, which is what this is.
In this case there are 2 x-crossings
{{{ 0 = 5x^2 - 1 }}}
{{{ 5x^2 = 1 }}}
{{{ x^2 = 1/5 }}}
{{{ x = 1/sqrt(5) }}}
{{{ x = -1/sqrt(5) }}}
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