已知a+b=3,则a²-b²+6b的值为____.
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![已知a+b=3,则a²-b²+6b的值为____.](/uploads/image/z/1252751-23-1.jpg?t=%E5%B7%B2%E7%9F%A5a%2Bb%3D3%2C%E5%88%99a%26%23178%3B-b%26%23178%3B%2B6b%E7%9A%84%E5%80%BC%E4%B8%BA____.)
已知a+b=3,则a²-b²+6b的值为____.
已知a+b=3,则a²-b²+6b的值为____.
已知a+b=3,则a²-b²+6b的值为____.
答:
a+b=3
a²-b²+6b
=(a+b)(a-b)+6b
=3(a-b)+6b
=3a-3b+6b
=3a+3b
=3(a+b)
=3*3
=9
a^2-b^2+6b
=(a+b)(a-b)+6b
=3(a-b)+6b
=3a-3b+6b
=3a+3b
=3(a+b)
=3*3
=9