100 lbs divided by 2.2 equals what

What is the value of the expression below? (81^2)^1/8

Which geometric principle is used to justify the construction below?

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