Question

halei ajutor pls dau coroana
30 pnct pentru alalaallaalalalalalalalalallaalalalalalalalalalalalalalallaalalalalalalallala care ma ajuta​

Answer 1

Răspuns:

Explicație pas cu pas:

Answer 2

$\bf a)\ \ =1+2+3+\ ...\ +50=\dfrac{50\cdot51}{2}=25\cdot51=1275\\ \\ \\ b)\ \ =3+6+9+\ ...\ +90=3(1+2+3+\ ...\ +30)=3\cdot\dfrac{30\cdot31}{2}=3\cdot15\cdot31=1395$