UC知道悬赏50分!!!!~!!!!!!!!!!!!!!!!50分!!!~~!~!~!!!!!
来源：百度知道 编辑：UC知道 时间：2024/05/09 15:52:16
因式分解:
2x^3-8x
a^2(x-y)+b^2(y-x)
(a-b)^2-25
81a^4-b^4
a^2b^4-0.25c^2
349^2-251^2
(45又1/2)^2-(55又1/2)
先化简,再求值:
(3x-2y)^2-(2x-3y)^2其中x=1,y=-2
(a+b/2)^2-(a-b/2),a=-1/8,b=2
过程和答案!(主要是过程,答案也重要)
还有,这是用完全平方公式计算的.
(m+n)^2-6(m+n)+9
x^2y^2-2xy+1
9-12t+4t^2
y^2+y+1/4
4xy^2-4x^2y-y^2
(a-b)^2+10(a-b)+25
(a^2+b^2)^2-9a^2b^2
4m^2-3n(4m-3n)
先因式分解,再计算求值:
9x^2+12xy+4y^2,x=4/3,y=-1/2
1/2+xy+1/2y^2,x+y=1
有人说,无论x取何实数,代数式x^2+y^2-10x+8y+45的值总是正数.你的看法如何?请说明理由.
(有过程和答案,另悬赏)
2x^3-8x
a^2(x-y)+b^2(y-x)
(a-b)^2-25
81a^4-b^4
a^2b^4-0.25c^2
349^2-251^2
(45又1/2)^2-(55又1/2)
先化简,再求值:
(3x-2y)^2-(2x-3y)^2其中x=1,y=-2
(a+b/2)^2-(a-b/2),a=-1/8,b=2
过程和答案!(主要是过程,答案也重要)
还有,这是用完全平方公式计算的.
(m+n)^2-6(m+n)+9
x^2y^2-2xy+1
9-12t+4t^2
y^2+y+1/4
4xy^2-4x^2y-y^2
(a-b)^2+10(a-b)+25
(a^2+b^2)^2-9a^2b^2
4m^2-3n(4m-3n)
先因式分解,再计算求值:
9x^2+12xy+4y^2,x=4/3,y=-1/2
1/2+xy+1/2y^2,x+y=1
有人说,无论x取何实数,代数式x^2+y^2-10x+8y+45的值总是正数.你的看法如何?请说明理由.
(有过程和答案,另悬赏)
因式分解:
2x^3-8x
=2x(x^2-4)
=2x(x+2)(x-2)
a^2(x-y)+b^2(y-x)
=a^2(x-y)-b^2(x-y)
=(x-y)(a^2-b^2)
=(x-y)(a+b)(a-b)
(a-b)^2-25
=(a-b+5)(a-b-5)
81a^4-b^4
=(9a^2+b^2)(9a^2-b^2)
=(9a^2+b^2)(3a+b)(3a-b)
a^2b^4-0.25c^2
=(ab^2+0.5c)(ab^2-0.5c)
349^2-251^2
=(349+251)(349-251)
=600*98
=58800
(45又1/2)^2-(55又1/2)
=(45.5+55.5)(45.5-55.5)
=100*(-10)
=-1000
先化简,再求值:
(3x-2y)^2-(2x-3y)^2其中x=1,y=-2
=(3x-2y+2x-3y)(3x-2y-2x+3y)
=(5x-5y)(x+y)
=(5+10)(1-2)
=-15
(a+b/2)^2-(a-b/2)^2,a=-1/8,b=2
=(a+b/2+a-b/2)(a+b/2-a+b/2)
=2a*b
=2*(-1/8)*2
=-1/2
看不懂....
2x^3-8x ＝2x(x^2-4)=2x(x-2)(x+2)
a^2(x-y)+b^2(y-x)=a^2(x-y)-b^2(x-y)=(x-y)(a^2-b^2)=(x-y)(a-b)(a+b)
(a-b)^2-25 =(a-b+5)(a-b-5)
81a^4-b^4=(9a^2-b^2)(9a^2+b^2)=(3a+b)(3a-b)(9a^2+b^2)
a^2b^4-0.25c^2难道是a的