Question

Calculeaza folosind Suma Gaus:
a) 2+4+6+...+140=
b)4+8+12+...+228=

Answer 1

2+4+6 ..............+140

s =2 ( 1+2+3......+70  )

s =2 * 70 (70+1 ) :2

s =70*71 =4970

b) 4+8+12..............+228

s = 4 ( 1+2+3 ........+57 )

s =4* 57 (57+1) :2

s =2*57*58 =6612