It should be 0.4 or 4/10 or 2/5
Solution:
The following information about the chain email can be Written as follows:
1 Person Email →→6 Persons (E-mail) →6² Persons (E-mail)→6³ Persons (E-mail)+.........few Days
As you can see the number of email sent starting from person 1 to 6 persons to 36 persons to 216 persons, forms a Geometric pattern.
So, Sum of the Series = 1 + 6 + 36 + 216 + 1296 +......+ for n days
= 
Formula for n terms of a geometric series
For, Common ratio (r)≥1
Sum of above geometric series up to n terms 
The fourth one: the slope from point O to point A is two times the slope of the line from point A to point B
A) Vectors are usually given in the form (x , y), therefore the x-component of v is 1.
B) Similarly to point A), the y-component of w is 6
C) the magnitude of the vector v+w is given by:
√[(x₁ + x₂)² + (y₁ + y₂)²] = √[(1 + (-2))² + (-3 + 6)²] = √(1 + 9) =√10
D) Compute -2 · v = (-2·1 , -2·(-3)) = (-2 , 6) = w
Therefore options B) and D) are true.
According to the logarithmic property of the base change, the corrected answer is option four or the last.
The logarithmic property of base change given that
loga (b) = logc (b) / logc (a)
Therefore, the same property applies to this problem and the correct expression for this question is:
y1 = log (x) / log (6)
y2 = log (x + 4) / log2
