Compute the directional derivative of the function g(x, y) = sin (pi(3x ? 2y)) at the point P( ? 1,? 2) in the direction (5/13,12/13) Be sure to use a unit vector for the direction vector. The directional derivative is (Type an exact answer, using n as needed.)

a and c

for infinitely many solutions we require both left and right sides to be equal

distribute and simplify

a

14 - 8x = 20 - 8x - 6 = 14 - 8x ← both sides equal so infinite solutions

b

6x - 54 = 6x - 54 + x = 7x - 54 ← not equal

c

4x + 16 = 4x + 10 + 6 = 4x + 16 ← both sides equal so infinite solutions

d

5x - 40 + 10 = 5x + 10

5x - 30 = 5x + 10 ← not equal

the answer is $23.63