先合并同列项,再求多项式的值 4m^2-4m+1-4+12m-9m^2,m=-1 (2)9x^2-12xy+4y^2,x=-二分之一,y=二分之一
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/02 10:56:52
![先合并同列项,再求多项式的值 4m^2-4m+1-4+12m-9m^2,m=-1 (2)9x^2-12xy+4y^2,x=-二分之一,y=二分之一](/uploads/image/z/5976143-71-3.jpg?t=%E5%85%88%E5%90%88%E5%B9%B6%E5%90%8C%E5%88%97%E9%A1%B9%2C%E5%86%8D%E6%B1%82%E5%A4%9A%E9%A1%B9%E5%BC%8F%E7%9A%84%E5%80%BC+4m%5E2-4m%2B1-4%2B12m-9m%5E2%2Cm%3D-1+%282%299x%5E2-12xy%2B4y%5E2%2Cx%3D-%E4%BA%8C%E5%88%86%E4%B9%8B%E4%B8%80%2Cy%3D%E4%BA%8C%E5%88%86%E4%B9%8B%E4%B8%80)
xRJ@~ l5$/"
z$(Z"V-x(ԃb$>يMM97ff&Td31tYbx?oS"^$M
ܤ,@{Iʢ1#O,7,#b
sdxsd|cl:!lP0ݓAiiv,Ja3poe-{bpr43$ؤP ݡAW$6y _ZG]Nچڏڬ6awr)^N[3.gT]|2+:`y
o
,et?oEml?6hr&|TDžjC^T
先合并同列项,再求多项式的值 4m^2-4m+1-4+12m-9m^2,m=-1 (2)9x^2-12xy+4y^2,x=-二分之一,y=二分之一
先合并同列项,再求多项式的值 4m^2-4m+1-4+12m-9m^2,m=-1 (2)9x^2-12xy+4y^2,x=-二分之一,y=二分之一
先合并同列项,再求多项式的值 4m^2-4m+1-4+12m-9m^2,m=-1 (2)9x^2-12xy+4y^2,x=-二分之一,y=二分之一
4m^2-4m+1-4+12m-9m^2,
=-5m^2+8m-3
=-5*1-1*8-3
=-16
9x^2-12xy+4y^2
=(3x-2y)^2
=(-1/2*3-2*1/2)^2
=(-5/2)^2
=25/4
4m^2-4m+1-4+12m-9m^2
=-5m²+8m-3
=-5*(-1)²+8*(-1)-3
=-5-8-3
=-16
(2)9x^2-12xy+4y^2
=(3x-2y)²
=[3*(-1/2)-2*(1/2)]²
=(-3/2-1)²
=25/4
1、原式=-5m^2+8m-3;当m=-1时,原式=-5*(-1)^2+8*(-1)-3=-16
2、原式=9x^2-12xy+4y^2,
当x=-1/2,y=1/2时,原式=9*(-1/2)^2-12*(-1/2)*(1/2)+4(1/2)^2=9/4+12/4+4/4=25/4