Question

efectuati: a) 4 • (2x + 7);
b) -3 (5 - 4x);
c) x² • (7x + 4).
a) (x + 5)²;
b) (6x - x)²;
c) (3x - 1)².
​

Answer 1

Răspuns:

Explicație pas cu pas:

a)  4 × ( 2 x + 7 ) = 4 × 2 x + 4 × 7 = 8 x + 28

b - 3 ( 5 - 4x) = - 3 × 5 - 3 × ( - 4 x ) = - 15 + 12 x = 12 x - 15

c)  x² · ( 7 x + 4 ) = x² · 7 x + x² · 4 = 7 x³ + 4 x²

____________________________________

a) ( x + 5)² = x² + 2 · x · 5 + 5² = x² + 10 x + 25

-> aplic formula ( a + b)² = a² + 2ab + b²

b)   ( 6 x - x)² = (5x)² = 5²·x² = 25 x²

c)  ( 3 x - 1 )² = (3x)² - 2 · 3 x + 1² = 9 x² - 6 x + 1