The electrons that produce the picture in a tv set are accelerated by a very large electric force as they pass through a small region in the neck of the picture tube. this region is 1.2 cm in length, and the electrons enter with a speed of 1 × 105 m/s and leave with a speed of 2.5 × 106 m/s. what is their acceleration over this 1.2 cm length? answer in units of m/s2

We use the formula:

a = (v^2 - u^2)/2s 

a = acceleration = ? 
v = final velocity = 2.5x10^6 
u = initial Velocity = 1x10^5 
s = distance traveled. = 0.012m 

To find the acceleration, we need to fill in the variables: 
a = ((2.5x10^6)^2 - (1x10^5)^2)/ 2* 0.012 = 260,000,000,000,000  m/s^2

Our acceleration is 2.6 × 10^14 m/s^2 

a and c

c is 100% but i am confused in a

i don't understand. explain it clearly