G is the point with coordinates (4, 16) on the curve with equation y = x².

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

i. (5, 25) 

ii. (4.5, 20.25) 

iii. (4.1, 16.81)

iv. (4.01, 16.0801) 

v. (4 + h, (4 + h)2)

b. What do you deduce about the gradient of the tangent at the point (4, 16)?