Explicație pas cu pas:
a)
[tex]0.1x + 0.01x + 0.001x + 0.0001x = {2}^{2} - 0.667 \\ (0.1 + 0.01 + 0.001 + 0.0001) = 4 - 0.667 \\ 0.1111x= 3.333 \implies \bf x = 30[/tex]
b)
[tex]x + 2x + 3x + ... + 20x = 100x - ( {( - 1 )}^{1} + ( { - 2})^{2} + ( { - 3})^{3} + ( { - 4})^{4}) \\ [/tex]
[tex](1 + 2 + 3 + ... + 20)x = 100x - ( - 1 + 4 - 27 + 256) \\ [/tex]
[tex]\frac{20 \cdot 21}{2} x = 100x - 232 \\[/tex]
[tex]210x = 100x - 232[/tex]
[tex]210x - 100x = - 232[/tex]
[tex]110x = - 232 \implies \bf x = - 2.1(09)[/tex]
