作业帮初二数学题求解!绝对给好评!
来源：学生作业帮 编辑：作业帮 分类：数学作业 时间：2024/05/21 17:49:41
初二数学题求解!绝对给好评!
D
原式=(-4*0.25)2009+(-0.125*8)2008*0.125
=(-1)2009+(-1)2008*0.125
=(-1)+0.125
=-0.875
ax^2-4ax+4a
=a(x^2-4x+4)
=a(x-2)^2
x²(x-y)+y²(y-x)
=x²(x-y)-y²(x-y)
=(x²-y²)(x-y)
=(x+y)(x-y)(x-y)
=(x+y)(x-y)²
4a²b²-(a²+b²-c²)²
=[2ab+(a²+b²-c²)][2ab-(a²+b²-c²)]
=(2ab+a²+b²-c²)(2ab-a²-b²+c²)
=[(a+b)²-c²][c²-(-2ab+a²+b²)]
=(a+b+c)(a+b-c)[c²-(a-b)²]
=(a+b+c)(a+b-c)[c+(a-b)][c-(a-b)]
=(a+b+c)(a+b-c)(c+a-b)(c-a+b)
原式=2a2+2ab-a2-2ab-b2
=a2-b2
将a=根号2008,b=根号2007代入,得
a2-b2=2008-2007=1
原式=(-4*0.25)2009+(-0.125*8)2008*0.125
=(-1)2009+(-1)2008*0.125
=(-1)+0.125
=-0.875
ax^2-4ax+4a
=a(x^2-4x+4)
=a(x-2)^2
x²(x-y)+y²(y-x)
=x²(x-y)-y²(x-y)
=(x²-y²)(x-y)
=(x+y)(x-y)(x-y)
=(x+y)(x-y)²
4a²b²-(a²+b²-c²)²
=[2ab+(a²+b²-c²)][2ab-(a²+b²-c²)]
=(2ab+a²+b²-c²)(2ab-a²-b²+c²)
=[(a+b)²-c²][c²-(-2ab+a²+b²)]
=(a+b+c)(a+b-c)[c²-(a-b)²]
=(a+b+c)(a+b-c)[c+(a-b)][c-(a-b)]
=(a+b+c)(a+b-c)(c+a-b)(c-a+b)
原式=2a2+2ab-a2-2ab-b2
=a2-b2
将a=根号2008,b=根号2007代入,得
a2-b2=2008-2007=1