计算:
(1)
;
(2)(y 2·y 3)÷(y·y 4);
(3)27 2×9 8÷(-3) 18;
(4)27 2n+1×3 5n÷ 81 2n-1;
(5)(x 4) 2÷(x 2) 2·x 2-x 2÷(-x 0)。
(1)原式=
;
(2)原式=y 5÷y 5=1;
(3)原式=3 6×3 16÷(-3) 18=3 22÷3 18=3 4=81;
(4)原式=3 3(2n+l)×3 5n÷3 4(2n-1)=3 6n+3×3 5n÷3 8n-4=3 6n+3+5n-8n+4=3 3n+7;
(5)原式=x 8÷x 4·x 2-x 2÷(-1)=x 8-4+2+x 2=x 6+x 2。