(1)a m+1 ?a=a m+2 故(1)错误; (2)b n+1 ?b n-1 =b 2n 故(2)错误; (3) 4 x 2n+2 (-
(4)[-(-a 2 )] 2 =a 4 故(4)错误; (5)(x 4 ) 4 =x 4 ?x 4 ?x 4 ?x 4 =x 16 故(5)正确; (6)a 5 a 6 ÷(a 5 ) 2 ÷a=a 11 ÷a 10 ÷a=1故(6)错误; (7)(-a)(-a) 2 +a 3 +2a 2 (-a)=-a 3 +a 3 -2a 3 =-2a 3 故(7)错误; (8)(x 5 ) 2 +x 2 x 3 =x 10 +x 5 故(8)错误; 所以正确的有2个, 故选A. |