... c , v 3c ( a + b c )3 c ( a + b c )3 4c + + a + b c (1) a + b (1) ta c: 3c 3 3c 3 (b + c a ) 4a b+c (2) Tng t: 3a 3 (c + a b )3 4b c+a (3) 3b 3 Cng (1), (2) v (3) ta suy P P = a ... 2 )2015 thnh dng P = a0 + a1 x + a2 x + + a2015 x 2015 Tớnh h s a2011 v tớnh S = a1+2a2+3a3++2015a2015 Ta cú P ( x ) = ( x ) 2015 2015 i = C2015 x i ( ) i=0 2015 i = a0 + a1 x + + a2015 x 2015 ... 4.(1,0 im): ( + 3i ) 1.(0,5 im) Tỡm tt c cỏc s thc b, c cho s phc ( 3i ) l nghim ca phng trỡnh z + 8bz + 64c = ( ) Ta cú + 3i = + 3i + 3. 3i + 3i = ( 3i ) ( 1+ i) = 3i + 3. 3i 3i = = 2i 12 (...