30.1  c) -1-i
      d) -3+4i
      e) -7i
      g) |Conjugate[3+sqrt(6)i]|
      h) 1-sqrt(3)i

30.2  a) solve 2x=-1, y=3
      b) solve x^2-y^2=1,xy=x

30.3  a) |-42|
      b) |i+1|
      c) |2i+2|
      e) |4+3i|
      g) |6*sqrt(3)-6*i|
      h) |1-i*sqrt(3)|

30.4  a) plot x^2+y^2=3^2
      b) plot x^2+y^2=3^2, x^2+y^2=(1/2)^2
      c) plot (x-1)^2+y^2=1^2
      d) plot (x)^2-y^2=4

30.5  a) i^20
      b) i^5+i+1
      e) i^2017-i
      f) (2+2i)^8
      g) (1+i)/(1-i) - (3-i)/(1+i) + 3i
      h) (2-i^3)^4/(i^8-i^6)^3 + i

30.6  b) (1-i)+(1+i), (1-i)-(1+i), (1-i)*(1+i), (1-i)/(1+i), |1-i|,|1+i|, Conjugate[1-i], Conjugate[1+i]
      c) (1+i)+(-3+2i), (1+i)-(-3+2i), (1+i)*(-3+2i), (1+i)/(-3+2i), |1+i|,|-3+2i|, Conjugate[1+i], Conjugate[-3+2i]
      e) (2-7i)+(3+4i), (2-7i)-(3+4i), (2-7i)*(3+4i), (2-7i)/(3+4i), |2-7i|,|3+4i|, Conjugate[2-7i], Conjugate[3+4i]
      f) (-4-i)+(-7-4i), (-4-i)-(-7-4i), (-4-i)*(-7-4i), (-4-i)/(-7-4i), |-4-i|,|-7-4i|, Conjugate[-4-i], Conjugate[-7-4i]
      g) (1+3i)+(1/(1+3i)), (1+3i)-(1/(1+3i)), (1+3i)*(1/(1+3i)), (1+3i)/(1/(1+3i)), |1+3i|,|1/(1+3i)|, Conjugate[1+3i], Conjugate[1/(1+3i)]
      h) ((1+i)/(1-i))+(i), ((1+i)/(1-i))-(i), ((1+i)/(1-i))*(i), ((1+i)/(1-i))/(i), |(1+i)/(1-i)|,|i|, Conjugate[(1+i)/(1-i)], Conjugate[i]

31.1  a) ExpToTrig[e^(i*0)]
      b) ExpToTrig[4*e^(i*pi/6)]
      c) ExpToTrig[8*e^(i*7*pi/6)]
      d) ExpToTrig[3*e^(i*(pi*(-5/2)))]

31.2  a) ExpToTrig[e^(i*(pi*(-1/2)))]
      c) ExpToTrig[e^(-i)]
      d) ExpToTrig[2*e^(i*(pi*(1/3)))]
      e) ExpToTrig[e^(i*(pi*(1/4)))-e^(i*(pi*(-1/4)))]
      f) ExpToTrig[2*e^(i*(pi*(1/4)))/(e^(i*(pi*(-3/4))))]
      h) ExpToTrig[(e^(i)-e^(-i))/(e^i+e^(-i))]