Tolong dijawab ya no. 6-10

6) (5x - 4)(5x + 4)
= 25x² + ( - 20 + 20 )x + (-4)(4)
= 25x² - 16

7) ( 3x - 4y)( 3x + 4y)
= 9x² + ( -12 + 12)xy + ( -4y)(4y)
= 9x² - 16y²

8) ( 3x - 5y)( 3x + 5y)
= 9x² + ( - 15 + 15)xy + ( -5y)(5y)
= 9x² - 25y²

9) ( 6x - 2y)( 6x + 2y)
= 36x² + ( - 12 + 12)xy + ( - 2y)( 2y)
= 36x² - 4y²

10) (ax - b)( ax + b )
= a²x² + ( ab - ab ) x + ( -b )( b)
= a²x² - b²