Which equation illustrates the identity property of multiplication? \( \begin{array}{l}(x+y i) \times z=(x z+y z i) \\ (x+y i) \times 0=0 \\ (x+y i) \times(z+w i)=(z+w i) \times(x+y i) \\ (x+y i) \times 1=(x+y i)\end{array} \)

The equation that illustrates the identity property of multiplication is \( (x+y i) \times 1=(x+y i) \). This property states that any number multiplied by one remains unchanged, which is essential in various mathematical contexts. In real-world applications, the identity property of multiplication helps in simplifying calculations and proving other mathematical principles. For instance, when dealing with complex numbers like \( x + yi \), knowing that multiplying by one keeps the number unchanged is fundamental when solving equations or manipulating algebraic expressions in engineering and physics.