Mathematics 9709 · AS & A Level · Complex numbers

Complex numbers — practice question

(i)[3]

Show all working and, without using a calculator, solve the equation $z^2 + (2\sqrt{6})z + 8 = 0$, writing your answers in the form $x + iy$, where $x$ and $y$ are exact real values.

(ii)[1]

Draw an Argand diagram and show the points that represent the roots.

(iii)[3]

The roots are represented by the points $A$ and $B$, with $O$ as the origin. Determine angle $AOB$.

(iv)[1]

Prove, from the given information, that triangle $AOB$ is equilateral.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Apply the quadratic formula, complete the square, or use $z=x+iy$ to determine a root, using $i^2=-1$

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI