Question

11
−
7
i
2
+
i
=
+
i

Answer 1

Interpretation 1 — i is the imaginary unit (i^2 = −1):

11 − 7i^2 + i = 11 − 7(−1) + i = 11 + 7 + i = 18 + i.

So the equation 11 − 7i^2 + i = +i becomes 18 + i = i, which implies 18 = 0 — false. Thus the equality does not hold.

Interpretation 2 — i is a variable (call it x):

11 − 7x^2 + x = x ⇒ 11 − 7x^2 = 0 ⇒ x^2 = 11/7 ⇒ x = ±√(11/7).