(a) complex numbers, a +ib, with a and b real, may be represented by (or are iso- morphic with) 2 x 2 matrices: () a b -b a ib show that this matrix representation is valid for (i) addition and (ii) multiplication. (b) find the matrix corresponding to (a +ib)-

Ahanging spring stretches by 35.0 cm when an object of mass 450 g is hung on it at rest. in this situation, we define its position as x = 0. the object is pulled down an additional 18.0 cm and released from rest to oscillate without friction. what is its position x at a moment 84.4 s later? express your answer in cm.