Rewrite without parentheses and simplify. \[ (w-9 x)^{2} \]

To rewrite and simplify the expression \( (w - 9x)^{2} \), you can use the formula for the square of a binomial, which states that \( (a - b)^{2} = a^{2} - 2ab + b^{2} \). Applying this to the expression: 1. Square the first term: \( w^{2} \). 2. Multiply the two terms and double it: \( -2 \cdot w \cdot 9x = -18wx \). 3. Square the second term: \( (9x)^{2} = 81x^{2} \). Putting it all together, the simplified expression is: \[ w^{2} - 18wx + 81x^{2} \]