Find an equation of the line tangent to the curve √xy + 4y = 39 at the point (1,9)?

i know the answer is y = -9/25 (x-1) +9, but how do you get 25?

2-3 6. use your equation to find how high tyler will have to climb to scale the peak. (4 points: 2 points for correctly substituting values, 2 points for the correct height)

How are algebraic expressions evaluated using substitution?

Which of the following transformations will make coincide with ? a. counter-clockwise rotation 90º about a, followed by a translation 5 units to the right b. translation 5 units to the right, followed by a reflection across the y-axis c. translation 5 units to the right, followed by a reflection across the x-axis d. translation 1 unit up and 5 units to the right, followed by a reflection across the x-axis