a curve has equation . find the gradients of the chords joining the following pair of points on the curve:

a) x = 1 and x = 1.01

with a) the coordinates were (1, 1) and (1.01, 1.05101005) and so it would follow:

which is = 5.101005

the textbooks answer for a) is 5.10100501

can someone tell me if i'm doing it wrong somewhere please? i really don't think i am. thanks