Answer:
B , A , C
Explanation:
(3x² - 7x + 14) + (5x² + 4x - 6) ← remove parenthesis
= 3x² - 7x + 14 + 5x² + 4x - 6 ← collect like terms
= (3x² + 5x²) + (- 7x + 4x) + (14 - 6)
= 8x² + (- 3x) + 8
= 8x² - 3x + 8 ← B
(2x² - 5x - 3) + (- 10x² + 2x + 7) ← remove parenthesis
= 2x² - 5x - 3 - 10x² + 2x + 7 ← collect like terms
= (2x² - 10x²) + (- 5x + 2x) + (- 3 + 7)
= - 8x² + (- 3x) + 4
= - 8x² - 3x + 4 ← A
(12x² - 2x - 13) + (- 4x² + 5x + 9) ← remove parenthesis
= 12x² - 2x - 13 - 4x² + 5x + 9 ← collect like terms
= (12x² - 4x²) + (- 2x + 5x) + (- 13 + 9)
= 8x² + 3x + (- 4)
= 8x² + 3x - 4 ← C