Question

2- Desenvolva os produtos notáveis e reduza os termos semelhantes
a) (x+7).(x-7) - x² + 50
b) (2a - 3b).(2a+3b) + 9b² +1
c)(3x + 1).(3x - 1) - 8x² + 1
d)(5x - 2)² + (x - 3).(x-2)
e)(x - 5)² - (x - 3)² - 16

Answer 1

a) (x+7).(x-7) - x² + 50 ==> x^2 - 49 - x^2 + 50 = + 1

b) (2a - 3b).(2a+3b) + 9b² +1 ==> 4a^2 - 9b^2 + 9b^2 +  1 ==> 4a^2 + 1

c)(3x + 1).(3x - 1) - 8x² + 1 ==> 9x^2 - 1 - 8x^2 + 1 ==> x^2

d)(5x - 2)² + (x - 3).(x-2) => 25x^2 - 20x + 4+x^2 - 5x + 6 => 29x^2 - 25x + 10

e)(x - 5)² - (x - 3)² - 16 => x^2 - 10x + 25 -(x^2 - 6x + 9 - 16 )

x^2 - 10x + 25 - x^2 + 6x - 9 + 16 ==> - 4x + 32