國二多項式運算!!!20點!!急~~

1.
[(-16x²/7) - (9x/8) + (13/9)] -[(5x²/2) + (7x/4) + (19/4)]
= (-16x²/7) - (9x/8) + (13/9) - (5x²/2) - (7x/4) - (19/4)
= (-32x²/14) - (9x/8) + (52/36) -(35x²/14) - (14x/8) - (171/36)
= -(67x²/14)- (23x/8) - (119/36)


2.
(-19x² + 16x - 8) + (x² + 13x + 10)
= -19x² + 16x - 8 + x² + 13x + 10
= -18x² + 29x + 2


3.
(-10x² + 7x - 4) - (-15x² + 10x + 6)
= -10x² + 7x - 4 + 15x² - 10x - 6
= 5x² - 3x - 10


4.
情況一：
(-10x² + 15x + 9) + (7x² - 3x)
= -10x² + 15x + 9 + 7x² - 3x
= -3x² + 12x + 9

情況一：
(-10x² - 15x + 9) + (7x² - 3x)
= -10x² - 15x + 9 + 7x² - 3x
= -3x² - 18x + 9


5.
(-6x - 20) - (-5x² - 14x + 15)
= -6x - 20 + 5x² + 14x - 15
= 5x² + 8x - 35


6.
(-9x² - 7x - 16) - (19x² + 11)
= -9x² - 7x - 16 - 19x² - 11
= -28x² - 7x - 27


7.
[(5x²/4) - (17x/15)] - [(10x²/9) + (7x/6) + (18/7)]
= (45x²/36) - (34x/30) - (40x²/36) - (35x/30) - (18/7)
= (5x²/36) - (69x/30) - (18/7)
= (5x²/36) - (23x/10) - (18/7)


8.
(-3x - 19) - (-5x² + 11x - 7)
= -3x - 19 + 5x² - 11x + 7
= 5x² - 14x - 12


9.
[(17x²/14) + (19x/18) + (12/7)] +[(16x²/15) - (5x/2) + (7/6)]
= (17x²/14) + (19x/18) + (12/7) + (16x²/15) - (5x/2) + (7/6)
= (255x²/210) + (19x/18) + (72/42)+ (224x²/210) - (45x/18) + (49/42)
= (479x²/210) - (26x/18) + (121/42)
= (479x²/210) - (13x/9) + (121/42)


10.
(6x² - 8x - 14) + (-4x² - 9x + 14)
= 6x² - 8x - 14 - 4x² - 9x + 14
= 2x² - 17x


11.
(8x² + x - 1) - (4x² - 10x - 13)
= 8x² + x - 1 - 4x² + 10x + 13
= 4x² + 11x + 12


12.
(17x² - 12x - 3) + (6x² - 4)
= 17x² - 12x - 3 + 6x² - 4
= 23x² - 12x - 7


13.
(20x - 9) - (4x² + 12x + 1)
= 20x - 9 - 4x² - 12x - 1
= -4x² + 8x - 10


14.
(-10x² + 11x + 3) + (-7x² - 3x)
= -10x² + 11x + 3 - 7x² - 3x
= -17x² + 8x + 3


15.
[-(8x²/3) + (7x/6) + (7/3)] +[-(5x²/2) + (5x/3) - (3/2)]
= -(8x²/3) + (7x/6) + (7/3) - (5x²/2) + (5x/3) - (3/2)
= -(16x²/6) + (7x/6) + (14/6) - (15x²/6) + (10x/6) - (9/6)
= -(31x²/6) + (17x/6) + (5/6)