Explanation:
c/(c - 5) = 4/(c - 4)
By Cross-multiplying,
We have c(c - 4) = 4(c - 5).
=> c² - 4c = 4c - 20
=> c² - 8c + 20 = 0
Since the discriminant is negative,
there are no real solutions for c.
However, there exist complex solutions for c.
Using the Quadratic Formula,
c = [8 ± √(-16)]/2
=> c = 4 ± √(-4)
=> c = 4 ± 4i or c = 4(1 ± i).