Explanation:
Linear function: y = mx + b
Quadratic function: y = ax² + bx + c
Exponential function: y = a(b)ˣ + c
Polynomial: y = aₙxⁿ + aₙ₋₁xⁿ⁻¹ + ... + a₁x¹ + a₀
f(x) = 2x + 3 - linear function and polynomial
f(x) = x² + 2x - 3 - quadratic function and polynomial
f(x) = 3ˣ - 2 - exponential function