a）g.e. = lim(x→+∞){1/[2(2^x)lnx]} + lim(x→+∞)[ln(x+1)/(2lnx)] = 0+1 = 1； b）g.e. = lim(x→+∞){x²(1/x)/[(3x²+2x)(1/x)]} = lim(x→+∞)[x/(3x+2)] = 1/3。
