Question

aratati ca urmatorele numere naturale sunt patrate perfecte: (a) 2 x ( 1 + 2 + 3 + 4 + 5 ) + 6 (b) (10 x 1 + 10 x 2 +........+ 10 x 19) : 19. VA ROG AJUTATIMA​

Answer 1

a) 2 x ( 1 + 2 + 3 + 4 + 5 ) + 6 =

= 2 x 5 x 6 : 2 + 6

= 5 x 6 + 6

= 6 (5 + 1)

= 6 x 6

= 6²

b) (10 x 1 + 10 x 2 +........+ 10 x 19) : 19 =

= 10 (1 + 2 + .. + 19) : 19

= 10 x 19 x 20 : 2 : 19

= 10 x 20 : 2

= 10 x 10

= 10²