已知a+b=3,则a2-b2+6b的值为_.

问题描述:

已知a+b=3,则a2-b2+6b的值为______.

a2-b2+6b
=(a+b)(a-b)+6b
=3(a-b)+6b
=3a+3b
=3(a+b)
=9.
故答案是:9.