(2a²+b²)+2[3a-(a²-b²)] 化简 求值 a是-1 b是2
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(2a²+b²)+2[3a-(a²-b²)] 化简 求值 a是-1 b是2
(2a²+b²)+2[3a-(a²-b²)] 化简 求值 a是-1 b是2
(2a²+b²)+2[3a-(a²-b²)] 化简 求值 a是-1 b是2
(2a²+b²)+2[3a-(a²-b²)]
=2a²+b²+2[3a-a²+b²]
=2a²+b²+6a-2a²+2b²
=3b²+6a
=3(2)²+6(-1)
=3(4)-6
=12-6
=6
(2a²+b²)+2[3a-(a²-b²)]
=2a²+b²+2[3a-a²+b²]
=2a²+b²+6a-2a²+2b²
=2a²-2a²+2b²+b²+6a
=3b²+6a
=3*2²+6*(-1)
=12-6
=6
去括号后合并同类项得
3b^2+6a
代入得6