Question

3x³-2x²-1怎么因式分解？

Answer 1

此题采用十字交叉法计算，得到此算式因式分解答案（x-1）（3x+1）

Answer 2

3(xxx-1)-2(xx-1)
=3(x-1)(xx+x+1)-2(x-1)(x+1)
=(x-1)(3xx+x+1)

Answer 3

3x³-2x²-1
=3x³-3-2x²+2
=3(x³-1)-2(x²-1)
=3(x-1)(x²+x+1)-2(x-1)(x+1)
=(x-1)[3(x²+x+1)-2(x+1)]
=(x-1)(3x²+x+1)

Answer 4

解：这道题目拆中间项-2x^3为-3x^3+x^3然后分组，即
x3x^3-2x^2-1
=(3x^3-3x^2)+(x^2-1)
=3x^2(x-1)+(x+1)(x-1)
=(x-1)(3x^2+x+1)
因为∆=2^2-4x3x1=4-12=-8<0，所以3x^2+x-1在实数范围内不能再分解。