Given that f is the right focus of hyperbola x216 − Y29 = 1, M is a moving point on the right branch of hyperbola, and a (5,4), the maximum value of 4mf-5ma is______ .

Given that f is the right focus of hyperbola x216 − Y29 = 1, M is a moving point on the right branch of hyperbola, and a (5,4), the maximum value of 4mf-5ma is______ .

Point F (5,0), eccentricity e = 54, let the distance from m to the right collimator be equal to Mn, then from the definition of hyperbola, we can get & nbsp; 4mf-5ma = 4.54mn-5 Ma = 5 (mn-ma), so when m, a, n are collinear, 5 (mn-ma) is the largest, and the maximum value is 5An = 5 (5-165 & nbsp;) = 9, so the answer is: 9