Question

2+5+8+11+.......+32=

Answer 1

Răspuns:

Explicație pas cu pas:

2+5+8+11+14+.......+32 = 187

(32-2) : 3 + 1 = 30 : 3 + 1 = 11 termeni are suma cu rația = 3

= 11 × (2+32) : 2 =

= 11 × 34 : 2 =

= 374 : 2 =

= 187

Answer 2

$2 + 5 + 8 + ... + 32 \\ = 2 +( 2 + 3 )+ (2 + 6 )+ ... + 2 + 30 \\ =\underbrace{ 2 + 2 + 2 + ... + 2} _{de \: 33 :3 = 11 \: ori } + 3 + 6 + ... + 30 \\ = 2 \times 11 + 3( 1 + 2 + ... + 10) \\ = 22 + 3 \times \frac{10 \times 11}{2} \\ = 22 + 3 \times 5 \times 11 \\ = 22 + 3 \times 55 \\ = 22 + 165 \\ = 187$