[tex]\displaystyle\bf\\c)\\\\\\\left(\frac{1}{7} \right)^{\b x}=\frac{2}{98}\\\\\\\left(\frac{1}{7} \right)^{\b x}=\frac{1}{49}\\\\\\\left(\frac{1}{7} \right)^{\b x}=\left(\frac{1}{7} \right)^{\b2}\\\\\\\implies~x=2[/tex]
