Question

Exercício: Calcule:
A) (x+9). (x-9)
B) (3x+5). (3x-5)
C) (2-7x). (2+7x)
D) (7-am). (7+am)
E) (2a+5). (2a-5)


alguém!?​

Answer 1

A) ( X + 9 ) × ( X - 9 ) = X × X = X²

+9 × -9 = -81

( X² - 81 )

B) ( 3x + 5 ) × ( 3x - 5 ) = 3x × 3x = 9x²

+5 × -5 = -25

( 9x² - 25 )

C) ( 2 - 7x ) × ( 2 + 7x ) = 2 × 2 = 4

+7x × -7x = -49x

( 4 - 49x )

D) ( 7 - am ) × ( 7 +am ) = 7 × 7 = 49

-am × + am = -am²

( 49 - am² )

E) ( 2a + 5 ) × ( 2a - 5 ) = 2a × 2a = 4a²

+5 × -5 = -25

( 4a² - 25 )

Sinais iguais (+)

Sinais diferentes (-)

ESPERO TER AJUDADO!!!!!!!