I heard this sum can be close using the Digamma function.
Please help me use it. i don′t know it.
sum of nth term: (1/(1.2.3)) + (1/(4.5.6)) + (1/(7.8.9)) + ...
solve the simultaneous equation
a)sin(x+y)=(1/((√2) ))
cos2x=((-1 )/2) for x and y ranging from 0 to 360 inclusive
b)if siny+cosx=x show that (d^2 y/dx^(2 ) ) =(x/((2−x^2 )^(3/2) ))