a,b ∈C : ab^− + b = 0 f : z′ = az^− + b
such that f(M) = M′
1. let z_A = z and z_(A′) = z′ and f(A) = A
show that 2Re(b^− z) = bb^−
(A is the set of invariant points and
describes a line (△) )
2. Deduce that (△) is a line with
gradient u^( →) with affix z_u^→ = ib
3. show that (z_(MM ′) /z_u ) = ((bb^− − 2Re(bz^− ))/(ibb^− ))
4. show that 2Re(b^− z_0 ) = bb^_ where
z_0 = ((z + z ′)/2)
5. Deduce that for M ∉ (△) , M is
a perpendicular bisector of [MM ′]
Let u_n be a set satisfying u_1 =1 & u_(n+1) =u_n +((ln n)/u_n ) , ∀ n ≥1
1. Prove that u_(2023) >(√(2023.ln 2023)).
2. Find: lim_(n→∞) ((u_n .ln n)/n).