Question

Hallar la suma de los quince primeros múltiplos de 5.

Answer 1

Sea x=5
Los primeros 15 multiplos de 5 serian x+2x+3x+4x+5x+6x+7x+8x+9x+10x+11x+12x+13x+14x+15x......(@)
Utilizando la formula de gauss
@=$\frac{15(16)x}{2} = (15)(8)(5)=15(40)=15(10)(4)=150(4)=600$