We are given [ H(x) = A(x) + B(x) - C(x) ]. Substitute with the given functions.
H(x) = (x³ - 5x + 4) + (2x² + 5x - 6) - (-x² + 3)
~Simplify
H(x) = (x³ - 5x + 4) + (2x² + 5x - 6) + (x² - 3)
~Combine like terms
H(x) = x³ + (2x² + x²) + (-5x + 5x) + (4 - 6 - 3)
~Simplify
H(x) = x³ + 3x² - 5
The answer is x³ + 3x² - 5
Best of Luck!