To find the value of \( M - N \), we start with the expressions for \( M \) and \( N \):
\[ M = 5x^2 + 7x - 4 \] \[ N = 3x^2 - 4x + 5 \]
Now, we subtract \( N \) from \( M \):
\[ M - N = (5x^2 + 7x - 4) - (3x^2 - 4x + 5) \]
We distribute the negative sign across the terms in \( N \):
\[ M - N = 5x^2 + 7x - 4 - 3x^2 + 4x - 5 \]
Next, we combine like terms:
-
For \( x^2 \) terms: \[ 5x^2 - 3x^2 = 2x^2 \]
-
For \( x \) terms: \[ 7x + 4x = 11x \]
-
For constant terms: \[ -4 - 5 = -9 \]
Combining all these results, we obtain:
\[ M - N = 2x^2 + 11x - 9 \]
Thus, the final value of \( M - N \) is:
\[ \boxed{2x^2 + 11x - 9} \]