Question

2+4+6+...+100-25x2.Va rog ajutatima

Answer 1

2+4+6+...+100=2(1+2+3+...+50)=2(50x51):2=2550
2550-25x2=2550-50=2500

Answer 2

Răspuns

Explicație pas cu pas:

2 + 4 + 6 + ..... + 100 - 25 × 2 = 2 500

= 2 × ( 1 + 2 + 3 + ...... + 50 ) - 50 =

= 2 × 50 × ( 1 + 50 ) : 2 - 50 =

= 50 × 51 - 50 =

= 50 × ( 51 - 1 ) =

= 50 × 50 =

= 50² → patrat perfect

= 2 500