Question

已知=3,則b的值為______________.

Answer 1

-5

解析：∵=3,

∴ax²+bx+1必有因式(x-1).設ax²+bx+1=a(x+c)(x-1)=a［x²+(c-1)x-c］=ax²+a(c-1)x-ac,

∴又==a(x+c)=a(1+c)=3,

∴解得即b=-5.