Question

S1=4+8+12+......+60+(3+6+9+........+49)

Repede

Clasa 5

Answer 1

4+8+12+...+60=4×(1+2+3+...+15)=4×15×16:2=30×16=480(1)

3+6+9+...+48+1=3×(1+2+3+...+16)+1=3×16:2×17+1=24×17+1=408+1=409(2)

,,=>" rezultă

Din (1) si (2)=> S1=480+409=889

Sper ca te-am ajutat !!

Answer 2

Răspuns:

Explicație pas cu pas:

S₁ = 4 + 8 + 12 + ..... + 60 + ( 3 + 6 + 9 + ..... + 48 )

S₁ =  4 × ( 1 + 2 + 3 + .... + 15 ) + 3 × ( 1 + 2 + 3 + ...... + 16)

S₁ = 4 × [ 15 × ( 1 + 15 ) : 2 ] + 3 × [ 16 × ( 1 + 16 ) : 2 ]

S₁ = 4 × ( 15 × 16 : 2 ) + 3 × ( 8 × 17 )

S₁ = 4 × ( 15 × 8 ) + 3 × 136

S₁ = 4 × 120 + 408

S₁ = 480 + 408

S₁ = 888