Question

sa se rezolve ecuatia x+3x+5x+ ...... +13x=-490
+explicatie va roog

Answer 1

x+3x+5x+ ...... +13x=-490

[tex] \it x+3x+5x+ ... +13x=-490 \Rightarrow x(1+3+5+7+9+11+13) =-490\Rightarrow \\ \\ \Rightarrow 49\cdot x=-490|_{:49} \Rightarrow x = -10 [/tex]

Answer 2

x + 3x + 5x + ...... + 13x = - 490

x (1 + 3 + 5 + ....+ 13) = - 490  

x × 7 ² = - 490

x × 49 = - 490

x = - 490 : 49

x = -10