Calculating various constants required to calculate x3
let f1 = f ( a ) ; let f2 = f ( b ) ; let f3 = f ( c ) ; let d1 = f1 - f3 ; let d2 = f2 - f3 ; let h1 = a - c ; let h2 = b - c ; let a0 = f3 ; let a1 = ( ( ( d2 * Math . pow ( h1 , 2 ) ) - ( d1 * Math . pow ( h2 , 2 ) ) ) / ( ( h1 * h2 ) * ( h1 - h2 ) ) ) ; let a2 = ( ( ( d1 * h2 ) - ( d2 * h1 ) ) / ( ( h1 * h2 ) * ( h1 - h2 ) ) ) ; let x = ( ( - 2 * a0 ) / ( a1 + Math . abs ( Math . sqrt ( a1 * a1 - 4 * a0 * a2 ) ) ) ) ; let y = ( ( - 2 * a0 ) / ( a1 - Math . abs ( Math . sqrt ( a1 * a1 - 4 * a0 * a2 ) ) ) ) ;