Question

3+6+9+.......+60/3+6+9+.......+90=?​

Answer 1

$\dfrac{3+6+9+\ ...\ +60}{3+6+9+\ ...\ +90}=\dfrac{\not3(1+2+3+\ ...\ +20)}{\not3(1+2+3+\ ...\ +30)}=\dfrac{\dfrac{20\cdot21}{2}}{\dfrac{30\cdot31}{2}}=\dfrac{20\cdot21}{30\cdot31}=\dfrac{42}{93}$

Answer 2

Răspuns:

42/93

Explicație pas cu pas:

3(1+2+...+20)/3(1+2+...+30)=

20*21/(30*31) **** =2*21/3*31=42/93

**** nu am mai pus/2 , ca se simplifica