Which one is not a linear equation? Choose the correct answer below. A. \( 0.03 x-0.07 x=0.30 \) B. \( 7 x+7 x=15 x \) (C. \( 2 x+7(x-1)=-3 x \) D. \( 8 x^{2}-3 x+3=0 \)

The correct answer is: **D. \( 8 x^{2} - 3 x + 3 = 0 \)** **Explanation:** A **linear equation** in one variable is an equation of the form \( ax + b = 0 \), where \( a \) and \( b \) are constants, and the highest power of \( x \) is 1. Let's evaluate each option: - **A. \( 0.03 x - 0.07 x = 0.30 \)** - Simplifies to \( -0.04x = 0.30 \), which is linear. - **B. \( 7 x + 7 x = 15 x \)** - Simplifies to \( 14x = 15x \), which is linear. - **C. \( 2 x + 7(x - 1) = -3 x \)** - Expands to \( 2x + 7x - 7 = -3x \), which simplifies to \( 9x - 7 = -3x \), and further to \( 12x = 7 \). This is linear. - **D. \( 8 x^{2} - 3 x + 3 = 0 \)** - Contains \( x^2 \), making it a **quadratic equation**, not linear. Therefore, **Option D** is **not** a linear equation. **Answer:** **D. \( 8 x^{2}-3 x+3=0 \)**