DE THI CUA BO GD Toan THCS Nam 2008

B= 3sin15o25'+ 4cos12o12'sin42o20'+ cos36o15' ; 2cos15o25'+ 3cos65o13'.sin15o12'+ cos31o33'.sin18o20' C = (1 + x x ), vôùi x = 143,08 ):( x+1 x -1 x x + x- x-1 10.1376 = 10 86 625 S = p(p - a)(p - b)(p - c); S = abc ) 4R (d1 ) : y = +1 x+ 2 (d 2) : y = a o = 1, a n+1 = a n+ -1 x2 an2 + an +1-1 vôùi n = 0,1,2, an 13x - 2610x - 2009x - 4030056 = 2 (x - x + 4017) (y + y + 1) = 4017 x = 2008 y= (1) (2) ... +1-1 vôùi n = 0,1,2, an 13x - 2610x - 2009x - 4030056 = 2 (x - x + 4017) (y + y + 1) = 4017 x = 2008 y= (1) (2)