Question 450245
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Hi, 
Standard Form of an Equation of an Hyperbola opening right and left is:  
{{{(x-h)^2/a^2 - (y-k)^2/b^2 = 1}}} 
where Pt(h,k) is a center  with vertices 'a' units right and left of center.
vertices at (-3,0) (3,0) and foci at (-11,0) (11,0)
 {{{ x^2/9 - y^2/b^2 = 1 }}} C(0,0) with vertices at (-3,0) (3,0)
foci at (-11,0) (11,0), that is: sqrt(9+b^2) = 11   b^2 = 112
  {{{ x^2/9 - y^2/112 = 1 }}}