1, solution: From the meaning of the question, the analytical formula is

y=a(x-2)？ +4,

Because the parabola passes through (1, 2),

∴2=a+4,a=-2，

The analytical formula is y=-2(x-2)? +4

2. Solution: Let the analytical formula be y=ax? Then +bx+c

- 1=c，c=- 1。

a+b= 1……①

a-b=3……②

①+②，get

2a=4，a=2。

b= 1-2，b=- 1。

∴ The analytical formula is y=2x? -x- 1。