To find the expression that represents \( L(x) - M(x) \), we start by substituting the expressions for \( L(x) \) and \( M(x) \):
- \( M(x) = 4x^2 - 8x + 17 \)
- \( L(x) = 5 - 2x^2 \)
Now, we calculate \( L(x) - M(x) \):
\[ L(x) - M(x) = (5 - 2x^2) - (4x^2 - 8x + 17) \]
Distributing the negative sign:
\[ L(x) - M(x) = 5 - 2x^2 - 4x^2 + 8x - 17 \]
Combine like terms:
- The \( x^2 \) terms: \( -2x^2 - 4x^2 = -6x^2 \)
- The \( x \) terms: \( 8x \) (there's no other \( x \) term to combine with)
- The constant terms: \( 5 - 17 = -12 \)
Putting it all together:
\[ L(x) - M(x) = -6x^2 + 8x - 12 \]
Now, we match this expression with the provided options. The correct expression is:
\[ \boxed{-6x^2 + 8x - 12} \]