Răspuns:
[tex]\bf a) ~2^{76} + 2^{78} + 2^{80} =[/tex]
[tex]\bf 2^{76}\cdot \big(2^{76-76} + 2^{78-76} + 2^{80-76}\big)=[/tex]
[tex]\bf 2^{76}\cdot \big(2^{0} + 2^{2} + 2^{4}\big)=2^{76}\cdot \big(1 + 4 +16\big)=[/tex]
[tex]\pink{\underline{~\bf 2^{76}\cdot21~}}[/tex]