Question 677707
It sounds like it could be either one.
The x-coordinate of the vertex is at
{{{ -b/(2a) }}} where the equation looks like
{{{ y = ax^2 + b*x + c }}}
The turning point is at (0,-7), so
{{{ -b/(2a) = 0 }}}
{{{ b = 0 }}}
Now I have
{{{ y = ax^2 + c }}}
{{{ -7 = a*0^2 + c }}}
{{{ c = -7 }}}
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It looks like {{{ a }}} can be any (+) or (-)
number since it just controls the shape
( narrow or wide ) and the direction
( open down or open up )
I'll say {{{ a = 3 }}}
{{{ y = 3x^2 -7 }}} answer
Here's the plot:
{{{ graph( 400, 400, -10, 10, -10, 10, 3x^2 - 7 ) }}}