多項式運算!!很急!!20點~~

1.
(3x + 12) - (-6x² + x + 19)
= 3x + 12 + 6x² - x - 19
= 6x² + 2x - 7


2.
(12x² + 11x - 3) - (-16x² - 17x + 14)
= 12x² + 11x - 3 + 16x² + 17x - 14)
= 28x² + 28x - 17


3.
(-11x² - 6x - 12) + (18x² + x - 18)
= -11x² - 6x - 12 + 18x² + x - 18
= 7x² - 5x - 30


4.
(-18x² + 12x) + (9x² + 20x - 3)
= -18x² + 12x + 9x² + 20x - 3
= -9x² + 32x - 3


5.
(-x² - 5x - 9) + (17x² + 5x + 3)
= -x² - 5x - 9 + 17x² + 5x + 3
= 16x² - 6

6.
(-6x - 5)(-11x² + 7x - 20)
= (-6x - 5)(-11x² + 7x - 20)
= -6x(-11x² + 7x - 20) - 5(-11x² + 7x - 20)
= 66x³ - 42x² +120 + 55x² - 35x + 100
= 66x³ + 13x² - 35x + 220


7.
(-15x - 4)(-5x + 7)
= -15x(-5x + 7) - 4(-5x + 7)
= 75x² - 105x + 20x - 28
= 75x² - 85x - 28


8.
(5x²)²
= 5² * (x²)²
= 25x⁴


9.
(9x/7) * [-(16x/5) + (6/5)]
= (9x/7)*[-(16x/5)] + (9x/7)*(6/5)
= (-144x²/35) + (54x/35)


10.
(13x - 14)²
= (13x)² - 2(13x)(14) + (14)²
= 169x² - 364x + 196


11.
(15x - 13)(15x + 13)
= (15x)² - (13)²
= 225x - 169


12.
[-(6x²/5) - (7/6)] [-(6x²/5) + (7/6)]
= [-(6x²/5)]² - (7/6)²
= (36x⁴/25) - (49/36)


13.
(-3x/2) * (-10x/9)
= [(-3x)(-10x)] / (2*9)
= 30x²/18
= 5x²/3


14.
(-15x²/2) * [(-4x/3) - (11/9)]
= (-15x²/2)*[(-4x/3)] - (-15x²/2)*(11/9)
= 10x³ + (55x²/6)


15.
(19x/7)²
= (19x)²/7²
= 361x²/49


分數的表示方式，應為「(分子)分之(分母)」。
例如：2x/3 是「3分之2x」，而不是「2x分之3」。