Solution to Quadratic Equation Problem

In this mathematical problem, we are given two equations involving the variables C, D, and a:

• C = 2a² – 5
• D = 3 – a

We are asked to find the expression for C – 2D, and the solution involves the following steps:

1. Substitute the given expressions for C and D into C – 2D: (2a² – 5) – 2(3 – a)
2. Expand and simplify the expression: 2a² – 5 – 6 + 2a = 2a² – 11 + 2a = 2a² + 2a – 11

The correct answer to this quadratic equation problem is choice (3): 2a² + 2a – 11.

Keywords: Quadratic Equation, Algebra, Mathematical Solution, Variable Substitution