Correct Answer : Murder

Points of evidence: 
– Now Cigarette in left hand shows he is a left handed person, He can`t shot himself by right hand.
– Now he is shown written something on a paper .but the table lamp is not connected with the wall socket.
– Now he is holding a cigarette in his left hand.he should have dropped the cigarette before shooting if it is a suicide.
– Now he is shown shot in his right side of head and there is blood in the wall on the right side.
– Now if it is a suicide the impact of bullet should have caused him to fall to his left side but he is shown fall to his right side.this shows a presence of third person who caused the body to fall on the right side.

if you look at the question we have equations as

2+9=711

14+6=820;

17+11=628

then 12+3=??

from Equation 1 

2+9=711

2+9=(2-9)(2+9)

= 711

here we used a formula called a+b=(a-b)(a+b)

similarly for remaining equations

Equation:2

14+6=(14-6)(14+6)=820

Equation:3

17+11=(17-11)(17+11)=628

now we have 12+3=??

12+3=(12-3)(12+3)=915

 

12+3=915 is the correct answer