Question

因式分解a^3+2a^2-12a+15

要过程，速度

Answer 1

答：

a^3+2a^2-12a+15
=(a^3+5a^2)-3a^2-12a+15
=(a+5)a^2-3(a^2+4a-5)
=(a+5)a^2-3(a+5)(a-1)
=(a+5)(a^2-3a+3)

Answer 2

a"' + 2a" - 12a + 15
= a"' + 5a" - 3a" - 12a + 15
= a"( a + 5 ) - 3a" - 15a + 3a + 15
= a"( a + 5 ) - 3a( a + 5 ) + 3( a + 5 )
= ( a + 5 )( a" - 3a + 3 )

或者
= a"' + 125 + 2a" - 12a - 110
= ( a + 5 )( a" - 5a + 25 ) + 2a" + 10a - 22a - 110
= ( a + 5 )( a" - 5a + 25 ) + 2a( a + 5 ) - 22( a + 5 )
= ( a + 5 )( a" - 5a + 2a - 22 + 25 )
= ( a + 5 )( a" - 3a + 3 )