Question

01. Efetue as seguintes multiplicações:

a. (4x + 2)(x - 3)
b. (2a + 2a - 3)(-a - 3)
c. (-3x + 5)(7x² + 4x + 3)
d. (3x² + 2x - 5)(x - 5)
e. (a² + 2ab)(a² - 2ab)​

Answer 1

Oie, Td Bom?!

a)

$= (4x + 2) \: . \: (x - 3) \\ = 4x \: . \: (x - 3) + 2(x - 3) \\ = 4x {}^{2} - 12x + 2x - 6 \\ = 4x {}^{2} - 10x - 6$

b)

$= (2a + 2a - 3) \: . \: ( - a - 3) \\ = 2a \: . \: ( - a - 3) + 2a \: . \: ( - a - 3) - 3( - a - 3) \\ = - 2a {}^{2} - 6a - 2a {}^{2} - 6a + 3a + 9 \\ = - 4a {}^{2} - 9a + 9$

c)

$= ( - 3x + 5) \: . \: (7x {}^{2} + 4x + 3) \\ = - 3x \: . \: (7x {}^{2} + 4x + 3) + 5(7x {}^{2} + 4x - 3) \\ = - 21x {}^{3} - 12x {}^{2} - 9x + 35x {}^{2} + 20x + 15 \\ = - 21x {}^{3} + 23x {}^{2} + 11x + 15$

d)

$= (3x {}^{2} + 2x - 5) \: . \: (x - 5) \\ = 3x {}^{2} \: . \: (x - 5) + 2x \: . \: (x - 5) - 5(x - 5) \\ = 3x {}^{3} - 15x {}^{2} + 2x {}^{2} - 10x - 5x + 25 \\ = 3x {}^{3} - 13x {}^{2} - 15x + 25$

e)

$= (a {}^{2} + 2ab) \: . \: (a {}^{2} - 2ab) \\ = (a {}^{2} ) {}^{2} - (2ab) {}^{2} \\ = a {}^{4} - 4a {}^{2} b {}^{2}$

Att. Makaveli1996