一、认真填一填 (每空 2分 ,共 2 4分 )1 .-5的相反数是 ,-0 .5的倒数是.2 .一件夹克标价为a元 .现按标价的 7折出售 .则实际售价用代数式表示为 :元 .3 .近似数 3 .2 5× 1 0 4 有个有效数字 .4.单项式 5a2 b ,-4ab2 ,3ab2 ,-4a2 b的和是.5.已知 (a -2 ) 2 + ｜ 2b+a｜=0 ,则 1. Conscientiously fill in the blank (2 points for each empty, total 24 points) The opposite number for 1 .-5 is that the inverse of -0.5 is .2. A jacket is priced at a. Now it is 30% off the list price. For sale, the actual selling price is expressed in algebraic terms as: Yuan.3. The approximate number of 3.2 5×10 4 has a significant figure. 4. The sum of the monomials 5a2 b, -4 ab2, 3 ab2, and -4a2 b is .5. Given (a -2) 2 + | 2b+a|=0, then