Question

Evaluate y=x^2+x-4, given x=2i

Answer 1

y = - 8 + 2i

Explanation:

Substitute x = 2i into the equation, noting i² = - 1

y = (2i)² + 2i - 4

= 4i² + 2i - 4

= 4(- 1) + 2i - 4

= - 4 + 2i - 4

= - 8 + 2i