Scan for seveled Pracsice in \( 76-26 \), combine like terms to simplify each expression. 18. \( 2.1 x^{2}+3-0.5 x^{2}-1 \) \( =\left(x^{2}-\square x^{2}\right)+(3-1) \) \[ =\square x^{2}+\square \]

Let's simplify the expression step by step. 1. **Identify the expression**: The expression given is \( 2.1 x^{2} + 3 - 0.5 x^{2} - 1 \). 2. **Combine like terms**: - The like terms for \( x^{2} \) are \( 2.1 x^{2} \) and \( -0.5 x^{2} \). - The constant terms are \( 3 \) and \( -1 \). 3. **Calculate the coefficients of \( x^{2} \)**: \[ 2.1 - 0.5 = 1.6 \] So, the combined term for \( x^{2} \) is \( 1.6 x^{2} \). 4. **Calculate the constant terms**: \[ 3 - 1 = 2 \] So, the combined constant term is \( 2 \). 5. **Final expression**: Putting it all together, we have: \[ 1.6 x^{2} + 2 \] Now, let's fill in the squares in your original format: \[ = \left(x^{2} - 0.5 x^{2}\right) + (3 - 1) \] \[ = 1.6 x^{2} + 2 \] Thus, the final answer is: \[ = 1.6 x^{2} + 2 \] In summary: - The coefficient of \( x^{2} \) is \( 1.6 \). - The constant term is \( 2 \).