Question

若x³+2kx+3k²;;含有因式x+1求k的值

Answer 1

设x³+2kx+3k²=(x+1)(x^2+ax+b)=x^3+(a+1)x^2+(a+b)x+b

则有：a+1=0

a+b=2k

3k^2=b

整理得3k^2-2k-1=0

k1=-1/3 k2=1