[tex]1)~~~2^{44}+2^{47}+2^{45}=2^{44}(1+2^3+2^1) =2^44(1+8+2)=\boxed{11\times 2^{44}} \\ \\
2) \\ \overline{ab51} + 2 \times \overline{ab}= \\
= 100 \times \overline{ab}+51+ 2 \times \overline{ab}= \\
=100 \times \overline{ab}+2 \times \overline{ab}+51 = \\
= \overline{ab}(100+2)+51 = \\
=102 \times \overline{ab} + 51 = \boxed{51(2 \times \overline{ab} + 1)~ \vdots ~51}~~semnul ~"~\vdots~"~= "divizibil" \\
cctd [/tex]