加油站管理规范2017:初一数学题，很简单~~~！！

4a-1+b^2-4a^2
=b^2-(4a^2-4a+1)
=b^2-(2a-1)^2
=(b+2a-1)(b-2a+1)
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2x^2-18=2(x^2-9)=2(x+3)(x-3)
1/3x^2-2x+3=1/3(x^2-6x+9)=1/3(x-3)^2
所以2x^2-18,1/3x^2-2x+3的公因式是x-3
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5^100/5^99-5^101=一个你不想知道的数字
但如果题目是
5^100/(5^99-5^101)
=5^100/5^99(1-5^2)
=5*(-24)
=-120
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x^2+y^2/2-xy
=1/2(2x^2+y^2-2xy)
=1/2(x^2+x^2-2xy+y^2)
=1/2[x^2+(x-y)^2]
当x=25,y=15时
=1/2[625+(25-15)^2]
=1/2(625+100)
=725/2
=362.5

1.解:原式=-4a^2+4a-1+b^2=-(4a^2-4a+1)+b^2=-(2a-1)^2+b^2=(b+2a-1)(a-2a+1)
2.解:公因式是(x-3) 注：“1/3x^2-2x+3”应是（1/3x^2-2x+3）吧
3.但如果题目是 5^100/(5^99-5^101) 则=-120
但如果题目是 5^100/5^99-5^101，
则=5-5^101=5(1- 5^100)
4.x^2+y^2/2-xy =1/2(2x^2+y^2-2xy)
=1/2(x^2+x^2-2xy+y^2)
=1/2[x^2+(x-y)^2]
将x=25,y=15代入上式得：x^2+y^2/2-xy =1/2(25^2+10^2）=725/2

1.解:原式=-4a^2+4a-1+b^2=-(4a^2-4a+1)+b^2=-(2a-1)^2+b^2=(b+2a-1)(a-2a-1)

2.解:公因式是(x-3)

3.解:-5/24 (此题题目含糊,可能有所差别)

4.解:50( 此题题目含糊,可能有所差别)