A rational function is any function which can be defined by a rational fraction, which is an algebraic fraction such that both the numerator and the denominator are polynomials
First you simply have to substitute 2 in replace of all the a's, and -2 in replace of all of the b's
4((2)2+2(-2))
Then you want to follow the order of operations, PEMDAS (Parantheses-Exponent-Multiplication-Division-Addition-Subtraction), and multiply within the parantheses.
4(4+(-4))
Next you will add within the parantheses (So add the 4 and -4 together)
4(0)
Lastly multiply
0
Your answer is 0
Hope this helps!
