因式分解：(1)3a^4-8a^2-16 (2)2x^3-x^2-15x (3)3x^2-10x-8 (4)2x^2+x-15 (5)6x^2-11x=3 （6）4x^2+5x-6(7)6x^2-17x+10 (8)-8x^2+6x+9用十字相乘法！！快点啊，各位~~好的快的追加50分！

Question

因式分解：(1)3a^4-8a^2-16 (2)2x^3-x^2-15x (3)3x^2-10x-8 (4)2x^2+x-15 (5)6x^2-11x=3 （6）4x^2+5x-6
(7)6x^2-17x+10 (8)-8x^2+6x+9
用十字相乘法！！快点啊，各位~~好的快的追加50分！

Answer 1

(1)3a^4-8a^2-16
=（3a²+4)(a²-4)
=（3a²+4)(a+2)(a-2)

(2)2x^3-x^2-15x
=x(2x²-x-15)
=x(2x+5)(x-3)

(3)3x^2-10x-8
=(3x+2)(x-4)

(4)2x^2+x-15
=(2x-5)(x+3)

(5)6x^2-11x+3
=(2x-3)(3x-1)

（6）4x^2+5x-6
=(4x-3)(x+2)

(7)6x^2-17x+10
=(6x-5)(x-2)

(8)-8x^2+6x+9
=-(8x²-6x-9)
=-(2x-3)(4x+3)