Răspuns:
a) [tex]\frac{2}{3}[/tex]
b) [tex]\frac{1}{4}[/tex]
Explicație pas cu pas:
a) [tex]\frac{1}{15} + \frac{2}{15} + \frac{3}{15} + \frac{4}{15} = \frac{1+2+3+4}{15} = \frac{10}{15} = \frac{2}{3}[/tex]
b) [tex]\frac{3}{4*25}+\frac{1}{2^{2}*5^{2}} + \frac{21}{2^{2}*25} = \frac{3}{4*25} + \frac{1}{4*25} + \frac{21}{4*25} = \frac{3+1+21}{4*25}=\frac{25}{4*25} = \frac{1}{4}[/tex]
