Răspuns:
Explicație pas cu pas:
a)x^2 +2x -11 = 6
3x+1 >= x^2 -x +1
x^2 -4x <= 0, x < 0, x <= 4
x =2
C(12;3) = 12*11*10/1*2*3 = 220
b) 3x+1 >= x^2 +2x -11
x^2 -x -12 <=0, delta = 1 +48 =49
x1,2 = (1 -+7)/2
x1 = -6/2 = -3 , x2 = 8/2 = 4
(x-4)(x+3) <=0, dar x >0 :
x -4 <= 0, x <= 4
x = 3
C(10;4) = C(10;6) comb.cmpl.
etc.
