Question

4) Devinvolva estes produtos i reduza os termos semelhantes
a) (x + 7)(x - 7) - x ^ 2 + 50

b) (3x - 1)(3x + 1) - 8x ^ 2 + 1

c)(2a - 3b)(2a + 3b) + 9b ^ 2 + 1​

Answer 1

Resposta:

$a) \: (x + 7) \times (x - 7) - {x}^{2} + 50 \\ {x}^{2} - 7x + 7x - 49 - {x}^{2} + 50 \\ = 1$

$b) \: (3x - 1) \times (3x + 1) - 8 {x}^{2} + 1 \\ 9 {x}^{2} + 3x - 3x - 1 - 8 {x}^{2} + 1 \\ {x}^{2}$

$c) \: (2a - 3b) \times (2a + 3b) + 9 {b}^{2} + 1 \\ 4 {a}^{2} + 6ab - 6ab - 9 {b }^{2} + 9 {b}^{2} + 1 \\ 4 {a}^{2} + 1$