关于、、、、【实数】的一些问题额、
1个回答
1. a(a+1)-(a²+2b)=1,得出a-2b=1
a²-4ab+4b²-2a+4b=(a-2b)²-2(a-2b)=-1
2. a、b、c为△ABC的三边,有b+c>a
(b+c)²>a², 所以b²+c²-a²+2bc＞0
3. 2^48-1=(2^6-1)(2^6+1)(2^12+1)(2^24+1)=63*65*(2^12+1)(2^24+1)
所以这两个数是63,65
4. 25（a-b）²-（a+b）²=(4a-6b)(6a-4b)=4(2a-3b)(3a-2b)
5.a²（x-y）+b²（y-x）=(x-y)(a²-b²)=(x-y)(a+b)(a-b)
6.πa²- πb²
7.5y²-15y+5=5(y²-3y+1)
=5[y-(3-√5)/2][y-(3+√5)/2](在实数范围内分解)
8.x(m-x)(m-y)-m(x-m)(y-m)=(m-x)(m-y)(x-m)=-(m-x)²(m-y)
9.-27m²n+9mn²-18mn=9mn(-3m+n-2)
10.(3x+1)²=9x²+1+6x,所以单项式可以是6x
11.a=b=c
12.(x+1/x)²=x²+1/x²+2
(1) x²+1/x²=14
(2)(x-1/x)²=x²+1/x²-2=12
13.化简得-3x²=-12
14.5x²+5x-15-24x-4x²-x²+4x=-15x-15=-15(x+1)
