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下列各式运算正确的是
[ ]
A.
B.
C.
D.
下列各式运算正确的是 ( )
A. B. C. D.
x2+x2=x5
x3-x2=x
x3x2=x6
D.(x3)2=x6
3a2+2a2=5a4
(a+3)2=a2+9
(a2)3=a5
3a2·2a=6a3
A.4x2y-5xy2=-xy2
B.-3a+5=2a
C.5mn-2mn+4mn=7mn
D.-x4+2x4=3x8