Resposta + Explicacao:
a) ( 2x + 7 )² = ( 2x + 7 ) . ( 2x + 7 )
= 4x² + 14x + 14x + 49
= 4x² + 28x + 49
b) ( x - y )² = ( x - y ) . ( x - y )
= x² - xy - xy + y²
= x² - 2xy + y²
c) ( 9x + 1 ) ( 9x – 1 )
= 81x² - 9x + 9x - 1
= 81x² - 1
d) ( 3y – 5 )² = ( 3y - 5 ) . ( 3y - 5 )
= 9y² - 15y - 15y + 25
= 9y² - 30y + 25
e) ( a - 4y )² = ( a - 4y ) . ( a - 4y )
= a² - 4ay - 4ay + 16y²
= a² - 8ay + 16y²
f) ( ab + a ) ( ab - a )
= a²b² - a²b + a²b - a²
= a²b² - a²
= b²
g) ( 2x + 3xy )² = ( 2x + 3xy ) . ( 2x + 3xy )
= 4x² + 6x²y + 6x²y + 9x²y²
= 4x² + 12x²y + 9x²y²
h) ( 10x - ab )² = ( 10x - ab ) . ( 10x - ab )
= 100x² - 10xab - 10xab + a²b²
= 100x² - 20xab + a²b²
i) (x – 4) (x +4)
= x² - 4x + 4x - 16
= x² - 16
j) (x + 2) (x – 2)
= x² - 2x + 2x - 4
= x² - 4
