Explicație pas cu pas:
a) ?
b)
[tex]B = {10}^{21} + {2}^{20} \times {5}^{21} + {2}^{21} \times {5}^{20} + {2}^{23} \times {5}^{20} = \\ [/tex]
[tex]= 10 \times {10}^{20} + {2}^{20} \times 5 \times {5}^{20} + 2 \times {2}^{20} \times {5}^{20} + {2}^{3} \times {2}^{20} \times {5}^{20} \\ [/tex]
[tex]= 10 \times {10}^{20} + 5 \times {10}^{20} + 2 \times {10}^{20} + 8\times {10}^{20} \\ [/tex]
[tex]= {10}^{20} \times (10 + 5 + 2 + 8) = {10}^{20} \times 25 \\ [/tex]
[tex]= {10}^{20} \times {5}^{2} = \red{\bf {(5 \times {10}^{10}) }^{2}}[/tex]
