Question

calculati valoarea expresiei

Answer 1

a) 
[(a^3-1)/2a^3 ]x[5a^2/(a^2+a+1)]=[(a-1)(a^2+a+1)]/2a^3}x[(5a^2)/(a^2+a+1)]=
=[5a(a-1)]/2
Dar a=-3    => [5(-3)(-3-1)]/2 =30/2  =15

b)
[(a^2-4)/(a^2-3a+9)] : [(a+2)(a^3+27)]=
[(a+2)(a-2)/(a^2-3a+9)] :[(a+2)/(a+3)(a^2-3a+9)]=
[(a+2)(a-2)/(a^2-3a+9)] x[(a+3)(a^2-3a+9)/(a+2)]=
(a-2)(a+3)
Dar a=0,5  => (0,5-2)(0,5+3) =1,5x3,5=5,25