若等差数列﹛an﹜满足anan+1=n2+3n+2,则公差为
问题描述：
若等差数列﹛an﹜满足anan+1=n2+3n+2,则公差为
答
令n=1
a1*a2=6.①
令n=2
a2*a3=12.②
②/①得 2a1=a3=a1+2d
∴a1=2d a2=3d
∴a1*a2=3d*3d=6
∴d2=1 d=±1