Question:

Key Concept: $a^b = 1$ when (i) $b = 0$: $x^2 + 4x - 60 = 0 \Rightarrow x = 6$ or $x = -10$ (base $\neq 0\checkmark$). (ii) $a = 1$: $x^2 - 5x + 4 = 0 \Rightarrow x = 1$ or $x = 4$ (any exponent). (iii) $a = -1$ and $b$ even: $x^2 - 5x + 6 = 0 \Rightarrow x = 2$ or $x = 3$; check: $x = 2$: $b = -48$ (even)$\checkmark$; $x = 3$: $b = -39$ (odd)$\times$. Sum $= 6 + (-10) + 1 + 4 + 2 = 3$.