Question

Вычислить:
а) 5+2i/1-2i
б) (1+i корень из 3) ^5

Answer 1

$a) \frac{5+2i}{1-2i} =\frac{(5+2i)*(1+2i)}{(1-2i)*(1+2i)} = \frac{5+10i+2i+4i^{2} }{1-4i^{2} } = \frac{5+10i+2i+4*(-1)}{1-4*(-1)}=\frac{5+10i+2i-4}{1+4} =\frac{1+12i}{5}=\frac{1}{5}+\frac{12}{5}i = 0.2 + 2,4i$

$b) (1+i\sqrt{3})^{5} = (1+i\sqrt{3})^{3+2} = (1+i\sqrt{3})^{3} * (1+i\sqrt{3})^{2} = (1+3\sqrt{3}i+9i^{2}+3i^{3} \sqrt{3} ) * (1+2\sqrt{3}i+3i^{2} ) = (1+3\sqrt{3}i+9*(-1)+3*(-i)\sqrt{3}) *(1+2\sqrt{3}i+3*(-1)) = (1+3\sqrt{3}i-9-3i\sqrt{3}) * (1+2\sqrt{3}i-3) = (1-9)*(1+2\sqrt{3}i-3)= -8(-2+2\sqrt{3}i) = 16-16\sqrt{3}i$