h(x)=x^2+2x-1, find h(x+9)-h(x), Does this make sense?

Question

This is a question I had written down and now do not understand what is being asked when I go back later.

Answer 1

h(x)=x^2+2x-1,

find h(x+9)-h(x)  to do this you plug in the values.

h(x+9) = (x + 9 )^2 + 2(x + 9) - 1  I multiplied (x+9)(x+9) for the first three terms and distributed s across the two terms in the parenthesis.

h(x+9) = x^2 + 18x + 81 + 2x + 18 - 1

h(x+9) = x^2 + 20x + 98  now you have to take this result and subtract h(x) from it

h(x+9) - h(x) =  x^2 + 20x + 98 - (x^2 + 2x -1)

h(x+9) - h(x) = x^2 + 20 x + 98 - x^2 - 2x + 1

h(x+9) - h(x) = 18x + 99