1. the curve y=ax^2+bx passes through the point (2,4) with gradient 8.

find a and b

2. show that if y=2x-x^2 then

y2^2y- 2dy+2y = 4(x+1)

dx^2 dx

3. A child's height h cm at age 8 years can be modelled by the equation

h= _a^4

500 + (a-1/2)^2 +55

for ages 11 ≤ a ≤ 16

Find the child's annual growth rate at age 12, and at age 15

I am completely stuck with what to do, so a little guidance with how to go about solving would be great. Thanks