(3x^2a - 4y^a z^3a) ^2 ...?
The answer is 9x⁴ᵃ - 24x²ᵃyᵃz³ᵃ + 16 y²ᵃz⁶ᵃ(a - b)² = a² - 2ab + b²(3x²ᵃ - 4yᵃz³ᵃ)² = (3x²ᵃ)² - 2 3x²ᵃ 4yᵃz³ᵃ + (4yᵃz³ᵃ)² = = 3²x²ᵃ² - 2 3 4 x²ᵃ yᵃz³ᵃ + 4²yᵃ²z³ᵃ² = = 9x⁴ᵃ - 24x²ᵃyᵃz³ᵃ + 16 y²ᵃz⁶ᵃ