tolong dijawab pake cara

1) A

2) B

3) A

4) 8x - 4 - 6x + 7
= 2x + 3 ( A )

5) 3x² - 5x + 7 - 2x² + 4x - 9
= x² - x - 2 ( B )

6) ( 6x - 5y - 2z ) + ( - 8x + 6y + 9z )
= 6x - 8x - 5y + 6y - 2z + 9z
= - 2x + y + 7z ( C )

7) ( 4x + 5y - 8z ) + ( x - 2y - 3z )
= 4x + x + 5y - 2y - 8z - 3z
= 5x + 3y - 11z ( A)

8) ( 5y - 3x - 4 ) - ( 5x - 3y + 7)
= 5y + 3y - 3x - 5x - 4 - 7
= 8y - 8x - 11
= - 8x + 8y - 11 ( C )

9) ( 2x + 3y ) - ( - 2x + 3y )
= 2x + 2x + 3y - 3y
= 4x ( C )

10) ( -8m²n³) × ( 2k³n⁴ )
= - 16k³m²n^7 ( D )