A student decided to start saving money. On the first day he saved 1 cent, on the second day an additional 2 cents, on the third day he saved an additional 4 cents. Each day he doubled the amount he saved the previous day. How much would he have saved total on day 20 (in dollars)?'

$ 524.288

Step-by-step explanation:

We will use the sum of a geometric series;

S = (first term)(1-r^n)/(1-r)

= 1(1 - 2^n) / (1 - 2)

= - (1 - 2^n)

= 2^n - 1

2 ^ (20 – 1)

2 ^ 19

= 524,288 cents

100 cents =  1 dollar

524,288 cents = 524,288/ 100 dollars

= $ 524.288

solution:

the given function is ,

      =

the three roots of this quadratic function is , 0 ,8 and 10.all the roots are real and rational.

if a quadratic equation is of the form ,

sum of the roots = a + b +c= 0+8+10=18=  

product of roots taken two at a time = a b + b c+ c a = 0+80+0=80 =  

product of roots = a b c = 0=  

there are 11 doors in a hall starting from 0 to 11.the entry in the hall is permitted through gate number 0 and exit is allowed through only gate number 8 and 10.so, three roots(0,8,10) of quadratic function is given by entry and exit route of this hall.