Question

11x + 12x + 13x +…+ 39x = 725 va rog :(

Answer 1

Răspuns:

Explicație pas cu pas:

11x + 12x + 13x +…+ 39x = 725

x*(11 + 12 + 13 + ... + 39) = 725

11 + 12 + 13 + ... + 39 = 1 + 2 + 3 +... + 39 - (1 + 2 + 3 + ... + 10)

= 39*40/2 - 10*11/2 = 39*20 - 5*11 = 780 - 55 = 725

x*725 = 725

x = 725 : 725 = 1

Answer 2

 Salutare!

Rezolvare:

11x+12x+13x+...+39x = 725

(11+12+13+...+39)x = 725

[(11+39)*28:2+(11+39):2]x = 725

(50*14+25)x = 725

(700+25)x = 725

725x = 725 |:725

x = 1

 Cu drag!