Monday, August 19, 2013

if alpha (α) and beta (β) are the roots of 2x^2-7x+10=0, find: (α) + (β) (α) x (β) (α)^2 + (β)^2 (α)^2 x (β) + (β)^2 x (α)

We'll find the roots of the quadratic using the
formula:



4ac))/(2a)



4ac))/(2a)


a,b,c are the coefficients of the
quadratic:


a = 2 ; b = -7 and c =
10



80))/(4)


We notice that the result of the difference under
the radical sign is negative, therefore the equation has complex
roots.


and
isqrt31)/4


We'll put and
beta



isqrt31)/4


We'll eliminate imaginary
parts:



14/4



7/2


We'll calculate the product of roots, that is a
special product which returns a difference of two
squares:



31i^2)/16


But =>
(49+31)/16alpha*beta = 5


We'll calculate
:



2alpha*beta


=>


We'll calculate
beta^2*alpha = alpha*beta(alpha + beta)



beta^2*alpha = 5*7/2 = 35/2


Therefore, the
requested results are:
alpha^2*beta + beta^2*alpha = 35/2

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