Question

determinati nr real x , stiind ca tgx ctgx+2 =0

Answer 1

Stim ca ctgx = 1/tgx tgx + 1/tgx + 2 = 0 tg²x + 2tgx + 1 = 0 Notam tgx = t t²+2t+1 = 0 Delta = 4-4*1*1 = 0 t1 = (-2+0)/2 = -1 Revenim la substitutie tgx = -1 => x € {arctg(-1) + k*pi | k € Z} x € { -pi/4 + k*pi | k € Z}