19. \( (4 a)^{2}= \) \( \qquad \) 20. \( \left(\frac{10 x^{5}}{5 x^{3}}\right)^{2}= \)

Calculate or simplify the expression \( (4a)^2 \). Simplify the expression by following steps: - step0: Solution: \(\left(4a\right)^{2}\) - step1: Use the properties of exponents: \(4^{2}a^{2}\) - step2: Evaluate the power: \(16a^{2}\) Calculate or simplify the expression \( \left(\frac{10x^5}{5x^3}\right)^2 \). Simplify the expression by following steps: - step0: Solution: \(\left(\frac{10x^{5}}{5x^{3}}\right)^{2}\) - step1: Divide the terms: \(\left(2x^{2}\right)^{2}\) - step2: Use the properties of exponents: \(2^{2}\left(x^{2}\right)^{2}\) - step3: Evaluate the power: \(4x^{4}\) The solutions to the given expressions are: 1. \( (4a)^2 = 16a^2 \) 2. \( \left(\frac{10x^5}{5x^3}\right)^2 = 4x^4 \)