Prove that the cross ratio of four complex numbers z1, z2, z3,
z4 is real if and only if the points z1, z2, z3, z4 lie on a line
or a circle. Then, compute the cross ratio of 1+√ 3, 1−3i, −1 − i
and 1 + i and determine whether they lie on a line, a circle, or
neither.
Let F be a field and let φ : F → F be a ring isomorphism. Define
Fix φ to be Fix φ = {a ∈ F | φ(a) = a}. That is, Fix φ is the set
of all elements of F that are fixed under φ. Prove that Fix φ is a
field. (b) Define φ : C → C by φ(a + bi) = a − bi. Take
for granted that φ is a ring isomorphism (we...
Let Z2 [x] be the ring of all polynomials with coefficients in Z2. List the elements of the field Z2 [x]/〈x2+x+1〉, and make an addition and multiplication table for the field. For simplicity, denote the coset f(x)+〈x2+x+1〉 by (f(x)) ̅.
Q1-Find all possible time domain signals corresponding
to the following z-transform:
X(z) = (z3 + z2 + 3/2 z + 1/2 ) /
(z3 + 3/2 z2 + 1/2 z)
Q2-A digital linear time invariant filter has the
following transfer function:
H(z) = (5 + 5z-1) / (1 - 3/8 z-1 + 1/16
z-2)
a) Find the impulse response if the filter is causal.