Question

let f be the function given by f(x)=x^2-4x
Find and simplifiy f(x+h)-f(x-h)/h

Please show all work Thank you

Answer 1

replace x with x+h first

(x+h)^2 -4(x+h)

minus (x-h)^2 -4(x-h)

first - second one divided by h

x^2 + 2xh +h^2 -4x -4h -x^2 +2xh-h^2 +4x -4h

(4xh-8h)h = 4x-8