The equation the fraction with numerator open paren x plus 1 close paren squared and denominator 225 plus the fraction with numerator open paren y plus 6 close paren squared and denominator 144 is equal to 1 represents an ellipse. Which points are the foci of the ellipse?

The ellipse is centered at (−1, −6), and its longer axis is horizontal because 225 is larger than 144. For an ellipse, c² = a² − b², so c² = 225 − 144 = 81 and c = 9. The foci are 9 units to either side of the center: (−1 − 9, −6) = (−10, −6) and (−1 + 9, −6) = (8, −6), which is choice B.

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