若a+b=3,则2a²+4ab+2b²-6的值是( ) A.12 B.6 C.3 D.0
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若a+b=3,则2a²+4ab+2b²-6的值是( ) A.12 B.6 C.3 D.0
解2a²+4ab+2b²-6
=2(a²+2ab+b²)-6
=2(a+b)²-6
=2×3²-6
=12
选A.
A!
2a²+4ab+2b²-6
=2(a+b)²-6
=2x9-6
=12
2a2+4ab+2b2-6
=2(a²+2ab+b²)-6
=2(a+b)²-6
=2*3²-6
=2*9-6
=12
选A
原式=2(a²+2ab+b²-3)=2[(a+b)²-3]=12
选A
过程详细简便清晰,望采纳