Question

calculati (x+2) la puterea 3

Answer 1

(x + 2)³ =

(x + 2) ·(x + 2) ·(x + 2) =(x² + 2x + 2x + 4)(x + 2 ) =(x² + 4x + 4)·(x + 2)

= x²·x + x²·2 + 4x·x + 4x·2 + 4·x + 4·2

= x³+ 2x²+ 4x²+ 8x + 4x + 8

= x³ + 6x² + 12x + 8

sau se utilizeaza formula de calcul prescurtat:

(a + b)³= a³+ b³+ 3ab· (a + b)

(x + 2)³  = x³ + 2³ +3 · x · 2·(x + 2) = x³ + 8 + 6x· (x + 2) = x³ + 8 + 6x² + 12x  = x³ + 6x² + 12x + 8