- #1
JPC
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Homework Statement
Un a sequence
0 < x < pi/2
U0 = 2cosx
Un+1 = quroot( 2 + Un)
1) Calculate U1, U2, and U3 in function of x (simplify maximum)
2) Show that Un = 2cos( x / 2^n)
Homework Equations
The Attempt at a Solution
1)
U1 = sqroot( 2 + 2cosx) = sqroot( 2 (1 + cosx))
= ?? (now , how do i simplify)
because , i should have when i have simplified a maximum :
U1 = 2cos(x/2)
= 2 (2cosx² - 1)
= 4cosx² - 2
So how do i go from sqroot( 2 + 2cosx) to 4cosx² - 2 ??