Trntukan hasil dari 5x-6y+8z(7x-9z)-21+9z-10

5x – 6y + 8z(7x-9z) – 21 + 9z – 10
=5x – 6y + 56xz – 72z^2 – 21 + 9z – 10
= -72z^2 + 56xz + 5x – 6y +9z -21-10
= – 72z^2 + 56xz + 5x – 6y + 9z-31