👤

Efectuează, folosind factorul comun:
a) 107.43 + 107 · 56 + 107
b) 46.39 + 46.47 +86.32 +86.23
c)2 +4 +6 + ... + 20


Răspuns :

a) 107 × 43 + 107 × 56 + 107 =

107 × ( 43 + 56 + 1 ) =

107 × ( 99 + 1 ) =

107 × 100 = 10700

b) 46 × 39 + 46 × 47 + 86 × 32 + 86 × 23 =

46 × ( 39 + 47 ) + 86 × ( 32 + 23 ) =

46 × 86 + 86 × 55 =

86 × ( 46 + 55 ) =

86 × 101 = 8686

c) 2 + 4 + 6 + ... + 20 =

2 × ( 10 × 11 : 2 ) =

2 × ( 110 : 2 ) =

2 × 55 = 110