Find the sum of the first 206 natural numbers

Need on this geometry question. explain how you did it.

Ineed with number 6 , explain how to get 1978

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