七年級(jí)數(shù)學(xué)升冪降冪排列試卷及答案

一、單項(xiàng)選擇題（每題2分，共20分）1.多項(xiàng)式\(3x^2y-5xy^2+y^3-2x^3\)按\(x\)的升冪排列是（）A.\(y^3-5xy^2+3x^2y-2x^3\)B.\(-2x^3+3x^2y-5xy^2+y^3\)C.\(y^3-5xy^2-2x^3+3x^2y\)D.\(-2x^3+y^3+3x^2y-5xy^2\)2.多項(xiàng)式\(4x^3-3x^2y^4+2xy-1\)按\(y\)的降冪排列為（）A.\(-3x^2y^4+4x^3+2xy-1\)B.\(-3x^2y^4+2xy+4x^3-1\)C.\(-1+4x^3+2xy-3x^2y^4\)D.\(-3x^2y^4+2xy-1+4x^3\)3.把多項(xiàng)式\(2x^2-3x+x^3\)按\(x\)的升冪排列正確的是（）A.\(x^3+2x^2-3x\)B.\(-3x+2x^2+x^3\)C.\(x^3-3x+2x^2\)D.\(2x^2+x^3-3x\)4.多項(xiàng)式\(5x^2y-3y^2-2x^3+6\)按\(x\)的降冪排列是（）A.\(-2x^3+5x^2y-3y^2+6\)B.\(5x^2y-2x^3-3y^2+6\)C.\(6-3y^2+5x^2y-2x^3\)D.\(-2x^3+6+5x^2y-3y^2\)5.多項(xiàng)式\(a^3-2a^2b^2+5b^3-3ab\)按\(b\)的升冪排列是（）A.\(a^3-3ab-2a^2b^2+5b^3\)B.\(5b^3-2a^2b^2-3ab+a^3\)C.\(a^3+5b^3-3ab-2a^2b^2\)D.\(-3ab-2a^2b^2+5b^3+a^3\)6.多項(xiàng)式\(3x^4-2x^3y+5xy^3-4y^4\)按\(x\)的升冪排列為（）A.\(-4y^4+5xy^3-2x^3y+3x^4\)B.\(3x^4-2x^3y+5xy^3-4y^4\)C.\(-4y^4+5xy^3+3x^4-2x^3y\)D.\(3x^4-4y^4+5xy^3-2x^3y\)7.把多項(xiàng)式\(x^3-2x^2y+3xy^2-y^3\)按\(y\)的降冪排列正確的是（）A.\(-y^3+3xy^2-2x^2y+x^3\)B.\(x^3-2x^2y+3xy^2-y^3\)C.\(-y^3+3xy^2+x^3-2x^2y\)D.\(x^3-y^3-2x^2y+3xy^2\)8.多項(xiàng)式\(2-3x^2+5x^3-4x\)按\(x\)的升冪排列是（）A.\(2-4x-3x^2+5x^3\)B.\(5x^3-3x^2-4x+2\)C.\(2+5x^3-3x^2-4x\)D.\(-4x-3x^2+5x^3+2\)9.多項(xiàng)式\(4x^2y-5xy^2+x^3-y^3\)按\(y\)的升冪排列是（）A.\(x^3+4x^2y-5xy^2-y^3\)B.\(-y^3-5xy^2+4x^2y+x^3\)C.\(x^3-y^3+4x^2y-5xy^2\)D.\(4x^2y-5xy^2-y^3+x^3\)10.把多項(xiàng)式\(6-2x^3+3x^2y-4xy^2\)按\(x\)的降冪排列正確的是（）A.\(-2x^3+3x^2y-4xy^2+6\)B.\(6-4xy^2+3x^2y-2x^3\)C.\(-2x^3+6+3x^2y-4xy^2\)D.\(3x^2y-4xy^2-2x^3+6\)二、多項(xiàng)選擇題（每題2分，共20分）1.以下關(guān)于多項(xiàng)式升冪降冪排列說(shuō)法正確的是（）A.升冪排列是按照某一字母的指數(shù)從小到大排列B.降冪排列是按照某一字母的指數(shù)從大到小排列C.多項(xiàng)式\(x^2+y^2\)按\(x\)升冪排列還是\(x^2+y^2\)D.多項(xiàng)式\(2x-3x^2+4\)按\(x\)降冪排列為\(-3x^2+2x+4\)2.多項(xiàng)式\(3x^3y-2x^2y^2+5xy^3-y^4\)，按\(x\)降冪排列時(shí)（）A.第一項(xiàng)是\(3x^3y\)B.第二項(xiàng)是\(-2x^2y^2\)C.第三項(xiàng)是\(5xy^3\)D.第四項(xiàng)是\(-y^4\)3.多項(xiàng)式\(4a^2b-3ab^2+a^3-b^3\)按\(b\)升冪排列正確的有（）A.先寫不含\(b\)的項(xiàng)\(a^3\)B.接著寫\(b\)的一次項(xiàng)\(4a^2b\)C.再寫\(b\)的二次項(xiàng)\(-3ab^2\)D.最后寫\(b\)的三次項(xiàng)\(-b^3\)4.下列多項(xiàng)式按\(x\)升冪排列的有（）A.\(1+2x+3x^2\)B.\(x^3-2x^2+3x-4\)C.\(-5+4x-3x^2+2x^3\)D.\(3+x+x^2\)5.多項(xiàng)式\(2x^4-3x^3y+4x^2y^2-5xy^3+y^4\)按\(y\)降冪排列后（）A.第一項(xiàng)是\(y^4\)B.第二項(xiàng)是\(-5xy^3\)C.第三項(xiàng)是\(4x^2y^2\)D.第四項(xiàng)是\(-3x^3y\)6.關(guān)于多項(xiàng)式\(a^3-3a^2b+3ab^2-b^3\)說(shuō)法正確的是（）A.按\(a\)降冪排列為\(a^3-3a^2b+3ab^2-b^3\)B.按\(b\)升冪排列為\(a^3-3a^2b+3ab^2-b^3\)C.按\(a\)升冪排列為\(-b^3+3ab^2-3a^2b+a^3\)D.按\(b\)降冪排列為\(-b^3+3ab^2-3a^2b+a^3\)7.多項(xiàng)式\(5x^2-3x^3+2x-1\)按\(x\)降冪排列的過(guò)程中（）A.先確定各項(xiàng)\(x\)的次數(shù)B.找到\(x\)次數(shù)最高項(xiàng)\(-3x^3\)排在首位C.然后依次排\(5x^2\)，\(2x\)，\(-1\)D.排列結(jié)果為\(-3x^3+5x^2+2x-1\)8.下列哪些是多項(xiàng)式\(x^3y-2x^2y^2+xy^3\)按\(x\)升冪排列的步驟（）A.觀察各項(xiàng)\(x\)的次數(shù)分別為\(3\)，\(2\)，\(1\)B.按\(x\)升冪排列為\(xy^3-2x^2y^2+x^3y\)C.先寫\(x\)次數(shù)最低項(xiàng)\(xy^3\)D.最后寫\(x\)次數(shù)最高項(xiàng)\(x^3y\)9.多項(xiàng)式\(6-4x+3x^2-x^3\)按\(x\)升冪排列后（）A.第一項(xiàng)是\(6\)B.第二項(xiàng)是\(-4x\)C.第三項(xiàng)是\(3x^2\)D.第四項(xiàng)是\(-x^3\)10.對(duì)于多項(xiàng)式\(m^3n-2m^2n^2+mn^3\)，按\(n\)降冪排列（）A.第一項(xiàng)是\(mn^3\)B.第二項(xiàng)是\(-2m^2n^2\)C.第三項(xiàng)是\(m^3n\)D.排列后為\(mn^3-2m^2n^2+m^3n\)三、判斷題（每題2分，共20分）1.多項(xiàng)式\(2x^2+3x+1\)按\(x\)升冪排列是\(1+3x+2x^2\)。（）2.多項(xiàng)式\(a^2b-ab^2+a^3-b^3\)按\(a\)降冪排列是\(a^3+a^2b-ab^2-b^3\)。（）3.多項(xiàng)式\(4x^3y-2xy^3+y^4\)按\(y\)升冪排列是\(4x^3y-2xy^3+y^4\)。（）4.把多項(xiàng)式\(3-2x+x^2\)按\(x\)降冪排列為\(x^2-2x+3\)。（）5.多項(xiàng)式\(x^4-2x^3y+3x^2y^2-4xy^3+y^4\)按\(x\)升冪排列后，\(y^4\)是第一項(xiàng)。（）6.多項(xiàng)式\(5a^3-3a^2b+2ab^2-b^3\)按\(b\)降冪排列是\(-b^3+2ab^2-3a^2b+5a^3\)。（）7.多項(xiàng)式\(2x^2y-3xy^2+x^3-y^3\)按\(y\)升冪排列時(shí)，\(x^3\)排在最前面。（）8.按\(x\)降冪排列多項(xiàng)式\(4x-3x^2+2x^3\)的結(jié)果是\(2x^3-3x^2+4x\)。（）9.多項(xiàng)式\(a^3b-2a^2b^2+3ab^3-b^4\)按\(a\)升冪排列為\(-b^4+3ab^3-2a^2b^2+a^3b\)。（）10.多項(xiàng)式\(3x^3-2x^2+5x-1\)按\(x\)升冪排列后是\(-1+5x-2x^2+3x^3\)。（）四、簡(jiǎn)答題（每題5分，共20分）1.簡(jiǎn)述多項(xiàng)式升冪排列和降冪排列的定義。答案：升冪排列是把一個(gè)多項(xiàng)式的各項(xiàng)按照某個(gè)字母的指數(shù)從小到大的順序排列；降冪排列是把各項(xiàng)按照某個(gè)字母的指數(shù)從大到小的順序排列。2.如何將多項(xiàng)式\(2x^2y-3xy^2+x^3-y^3\)按\(x\)降冪排列？答案：先看各項(xiàng)\(x\)的次數(shù)，\(x^3\)次數(shù)為\(3\)，\(2x^2y\)次數(shù)為\(2\)，\(-3xy^2\)次數(shù)為\(1\)，\(-y^3\)不含\(x\)。按\(x\)降冪排列為\(x^3+2x^2y-3xy^2-y^3\)。3.多項(xiàng)式\(4a^3-3a^2b+5ab^2-b^3\)按\(b\)升冪排列的步驟是什么？答案：先確定各項(xiàng)\(b\)的次數(shù)，不含\(b\)的項(xiàng)\(4a^3\)排首位，接著是\(b\)一次項(xiàng)\(-3a^2b\)，再是\(b\)二次項(xiàng)\(5ab^2\)，最后是\(b\)三次項(xiàng)\(-b^3\)，排列為\(4a^3-3a^2b+5ab^2-b^3\)。4.把多項(xiàng)式\(3x^4-2x^3y+4x^2y^2-5xy^3+y^4\)按\(y\)降冪排列，并說(shuō)明理由。答案：按\(y\)降冪排列為\(y^4-5xy^3+4x^2y^2-2x^3y+3x^4\)。理由是根據(jù)降冪排列定義