Question

拜托啦，马上要，要过程，写纸上

Answer 1

10. 原式 = 6a³-12a²+9a-6a³-8a²
= -20a²+9a
因为a = -2
原式=-20×(-2)²+9(-2) = -80-18 = -98

11. 33
∵原式 = -ab²(a²b^4 - ab² -1)
= -ab²[(ab²)²-ab²-1]
因为ab²=-3
原式 = 3×[(-3)²-(-3)-1] = 3× (11) = 33

12. 1.5
原式 = -6x^4 + 2ax³+12x²-3x³+x²
= -6x^4 + (2a-3)x³+13x²
因为没有x³项，
所以2a-3 = 0
a = 3/2 = 1.5

13.
(1) A·B+A·C = (-2x²)(x²-3x-1)+(-2x²)(-x+1)
= (-2x²)[(x²-3x-1)+(1-x)]
= (-2x²)(x²-4x)
= -2x^4 + 8x³
(2) A·(B-C) = (-2x²)[(x²-3x-1)-(-x+1)]
= (-2x²)(x²-2x-2)
= -2x^4+4x³+4x²