If a1 = 1 and an+1= 2an + 5, n = 1, 2 .. , then a100 is equal to ?	Choose the most appropriate option:
A) 5*2^99-6
B) 5*2^99+6
C) 6*2^99+5
D) 6*2^99-5
E) 6*2^99-6
a(n+1)= 2a(n) + 5   Even+Odd=Odd   Therefore all the values are Odd. A, B and E out.   a(2)=2+5= 
<gadget id="calculator">2+5</gadget>
<output>7</output>
7   Now lets take a2 and try solving it with the equations in C and D. Note they are similar and only differ by the sign before 5. So we have to only decide if our equation takes + or - 5.   Now, the equation in C and D looks like this 6*2^99 + (or -) 5.   In other words, a100=6*2^(n-1) + (or -) 5.   Now a2=7=6*2^1 +(or-) 5   7=12+(or-)5   Therefore the sign has to be -   Answer: 6*2^99-5
<result>D</result>
If a1 = 1 and an+1= 2an + 5, n = 1, 2 .. , then a100 is equal to ?