6.1同底数幂的乘法1.计算a-2·a4的结果是()A.a-2B.a2C.a-8D.a82.若x≠y,则下面各式不能成立的是()A.(x-y)2=(y-x)2B.(x-y)3=-(y-x)3C.(x+y)(x-y)=(x+y)(y-x)D.(x+y)2=(-x-y)23.a16可以写成()A.a8+a8B.a8·a2C.a8·a8D.a4·a44.下列计算中正确的是()A.a2+a2=a4B.x·x2=x3C.t3+t3=2t6D.x3·x·x4=x75.下列题中不能用同底数幂的乘法法则化简的是()A.(x+y)(x+y)2B.(x-y)(x+y)2C.-(x-y)(y-x)2D.(x-y)2·(x-y)3·(x-y)6.已知xn-3·xn+3=x10,求n的值.7.已知2m=4,2n=16.求2m+n的值.1/2参考答案1.B;2.C;3.C;4.B;5.B;6.n=5;7.64.2/2