hello. please can you help me with number 2

151 (2) Sketch the domain of the function f (I, y) = - VAr2 + y2 - 4 121 (3) A rectangular box has sides of length r, y and z. Write down an expression for the length of the body diagonal L in terms of r, y and z. If sides r and y are increasing by 2 cm/s and side z is decreasing by 3 cm/s, what is the rate of change of L when a = 2 cm, y = 3 em and z = 3 cm. 141 (4) If f and g are twice differentiable functions of a single variable, show that the function u(x,t) - f(x kf) + g(r + kt) is a solution of the wave equation un - ku, 141 (5) Prove that the set S = (X C R" Ax = Ax] is a subspace of R" 151 6) Given that the vectors u - [1.2.3] v - [2.3. 1', w = [1. 2. IJ' and x = [0.1. 1]' are linearly dependent. find integer coefficients ki. ke, ka and ky all not zero such that 151 huthvthaw tkix = 0