Chapter D2.4, Problem 53E

43–46. Directions of change Consider the following functions f and points P. Sketch the xy-plane showing P and the level curve through P. Indicate (as in Figure 15.52) the directions of maximum increase, maximum decrease, and no change for f. ■ 45. f(x, y) = x² + xy + y² + 7; P(−3, 3)

EX-let d'be ametric on a vector space X induced from a norm hx and d defind by a Slab)= {od (a, if a = b (a,b)+is ab Show that cannot be induced froman norm on X. 2) let à be trivel metric show that I cannot be induced from an norm on X- 3) let M be closed subspace of anormed spacex Construct the space X/Mas a normed space. 4) let Mix be vector space of 2x3 matrices on R write with Prove convex set and hyper Plane of M 5) show that every a finite dimension subspace of anormed space is closed.

please do #48

43–46. Directions of change Consider the following functions f and points P. Sketch the xy-plane showing P and the level curve through P. Indicate (as in Figure 15.52) the directions of maximum increase, maximum decrease, and no change for f. ■ 45. f(x, y) = x² + xy + y² + 7; P(−3, 3)

plese do #48

43-46. Directions of change Consider the following functions f and points P. Sketch the xy-plane showing P and the level curve through P. Indicate (as in Figure 15.52) the directions of maximum increase, maximum decrease, and no change for f. T 45. f(x, y) = x² + xy + y² + 7; P(−3, 3)

Solve the differential equation by variation of parameters 3x2y" + 7xy' + y = x2 - x

2 x² + 9 d x 1 x +9 dx

How did you get a(k+1) term?