PP!!

Algebra Level 3

Happy New Year in advance!


The answer is 3.

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2 solutions

U Z
Dec 29, 2014

α = a , β = b \alpha=a , \beta=b

x 2 3 x + 1 = 0 x^2 - 3x + 1=0

a 2 3 a + 1 = 0 a^2 - 3a + 1 =0

b 2 3 b + 1 = 0 b^2 - 3b + 1 =0

a 2016 3 a 2015 + a 2014 = 0 a^{2016} - 3a^{2015} + a^{2014} = 0

b 2016 3 b 2015 + b 2014 = 0 b^{2016} - 3b^{2015} + b^{2014} = 0

( a 2016 + b 2016 ) + ( a 2014 + b 2014 ) = 3 ( a 2015 + b 2015 ) (a^{2016} + b^{2016}) + (a^{2014} + b^{2014}) = 3(a^{2015} + b^{2015})

G i v e n e x p r e s s i o n = 3 Given ~ expression ~ = 3

Let P n = α n + β n S 1 = α + β S 2 = α β { P }_{ n }\quad =\quad \alpha ^{ n }+{ \beta }^{ n }\\ { S }_{ 1 }\quad =\quad \alpha +\beta \\ { S }_{ 2 }\quad =\quad \alpha \beta

Now, Using Newton's Sums: P n = P n 1 S 1 P n 2 S 2 , n 3 { P }_{ n }\quad ={ \quad P }_{ n-1 }{ S }_{ 1 }\quad -\quad { P }_{ n-2 }{ S }_{ 2 },\quad \forall \quad n\ge 3

In our case, S 1 = 3 , S 2 = 1 { S }_{ 1 }\quad =\quad 3,\quad { S }_{ 2 }\quad =\quad 1

Now, in the given fraction, α 2014 + β 2014 + α 2016 + β 2016 α 2015 + β 2015 = P 2014 + P 2016 P 2015 = P 2014 + P 2015 S 1 P 2014 S 2 P 2015 = P 2014 + P 2015 ( 3 ) P 2014 ( 1 ) P 2015 = P 2015 ( 3 ) P 2015 = 3 \frac { { \alpha }^{ 2014 }+{ \beta }^{ 2014 }+{ \alpha }^{ 2016 }+\beta ^{ 2016 } }{ { \alpha }^{ 2015 }+{ \beta }^{ 2015 } } \\ \\ =\quad \frac { { P }_{ 2014 }+{ P }_{ 2016 } }{ { P }_{ 2015 } } \\ \\ =\quad \frac { { P }_{ 2014 }+{ P }_{ 2015 }{ S }_{ 1 }-P_{ 2014 }{ S }_{ 2 } }{ { P }_{ 2015 } } \\ \\ =\quad \frac { { P }_{ 2014 }+{ P }_{ 2015 }(3)-P_{ 2014 }(1) }{ { P }_{ 2015 } } \\ \\ =\quad \frac { { P }_{ 2015 }(3) }{ { P }_{ 2015 } } \\ \\ =\quad 3

CHHERS!:)

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