F is the point with coordinates (3, 9) on the curve with equation y = x².

a Find the gradients of the chords joining the point F to the points with coordinates:

i. (4, 16) 

ii. (3.5, 12.25) 

iii. (3.1, 9.61)

iv. (3.01, 9.0601) 

v. (3 + h, (3 + h)²)

b. What do you deduce about the gradient of the tangent at the point (3, 9)?