将2(x+y)-3(x-y)-4(x+y)+5(x-y)-3(x-y)合并同类项得( )A.-3x-yB.-2(x+y)C.-x+yD.-2(x+y)-(
题型:单选题难度:简单来源:不详
将2(x+y)-3(x-y)-4(x+y)+5(x-y)-3(x-y)合并同类项得( )A.-3x-y | B.-2(x+y) | C.-x+y | D.-2(x+y)-(x-y) |
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答案
A |
解析
先合并同类项,再去括号. 解:原式=2(x+y)-3(x-y)-4(x+y)+5(x-y)-3(x-y) =-2(x+y)-(x-y) =-2x-2y-x+y =-3x-y 故答案选A。 |
举一反三
若-4x2y和-23xmyn是同类项,则m,n的值分别是( )A.m=2,n=1 | B.m=2,n=0 | C.m=4,n=1 | D.m=4,n=0 |
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下列各式中,去括号正确的是( )A.x2-(2y-x+z)= x2-2y2-x+z | B.3a-[6a-(4a-1)]=3a-6a-4a+1 | C.2a+(-6x+4y-2)=2a-6x+4y-2 | D.-(2 x2-y)+(z-1)=-2 x2-y-z-1 |
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.已知多项式A=x2+2y2-z2,B=-4x2+3y2+2z2,且A+B+C=0,则C为( )A.5x2-y2-z2 | B.3x2-5y2-z2 | C.3x2-y2-3z2 | D.3x2-5y2+z2 |
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如果与是同类项,那么m= ;n= ; |
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