已知a-b=3,则a²-b²-6b=

已知a-b=3,则a²-b²-6b=
已知a-b=3,则a²-b²-6b=

已知a-b=3,则a²-b²-6b=
a²-b²-6b
=(a-b)(a+b)-6b
=3(a+b)-6b
=3a+3b-6b
=3a-3b
=3(a-b)
=3*3
=9

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9 ，因式分解即可

a-b=3
a=b+3
a²-b²-6b
=(b+3)²-b²-6b
=b²+6b+9-b²-6b
=9

∵a-b=3
∴a=b+3
∴a²-b²-6b=(b+3)²-b²-6b=b²+6b+9-b²-6b=9

a-b=3
a=b+3
a平方-b平方-6b=(b+3)平方-b平方-6b
=9