Determine the surface area of a square-based pyramidal candle with a base side length of 8 cm
and a slant height of 10 cm.

Find the directions in which the function increases and decreases most rapidly at upper p 0p0. then find the derivatives of the function in these directions. f(x,y)equals=x squared plus xy plus y squaredx2+xy+y2, upper p 0p0left parenthesis 1 comma negative 4 right parenthesis