Question

3-Desenvolva o produto da soma pela diferença de dois termos:
a) (x + 9).(x –9) =
b) (m –1).(m + 1) =
c) (3x + 5).(3x -5) =
d) (2 –7x).(2 + 7x)
alguem me ajuda pfv

Answer 1

Resposta:

a) (x + 9).(x –9) =

x × x + x × ( -9) + x × x + 9 × x - 9 × x - 9 × 9 = 0

x^2 - 9x + x^2 + 9x - 81 = 0

2x^2 - 81 = 0

b) (m –1).(m + 1) =

m × m + m × 1 - 1 × m - ( -1 ) × 1= 0

m^2 + m - m + 1 = 0

m^2 + 1 = 0

c) (3x + 5).(3x -5) =

3x × 3x + 3x × ( -5 ) + 3x × 3x + 5 × ( -5 ) = 0

9x^2 - 15x + 9x^2 - 25 = 0

18x^2 - 15x -25 = 0

d) (2 –7x).(2 + 7x) =

2 × 2 + 2 × 7x - 7x × 2 - 7x × 7x = 0

4 + 14x - 14x - 49x^2 = 0

49x^2 + 4 = 0