因式分解--

( x^2+3 x)^2- 2(x^2+3x)-8      

(x^2+4)^2-16x^2       

x^3-8     

x^2-6x+8y+y^2+25=0 求根号２ x－３y　　

100^2 -99^2 +98^2 -97^2 + ......+2^2 -1^2 

1.原式=(x²+3x-4)(x²+3x+2)=(x+4)(x-1)(x+1)(x+2)

2.=(x²+4-4x²)(x²+4+4x²)=(4-3x²)(4+5x²)

3.=(x-2)(x²+2x+4)

4.=(x-3)²+(y+4)²=0,所以，x=3，y=-4，求出来是3根号2

5.=(100+99)(100-99)+(98+97)(98-97)+……+(2+1)(2-1)=199+195+191+……+3=(3+199)*50/2=5050

(1)

=(x^2+3 x-1)^2-3^2

=(x^2+3 x+2)(x^2+3 x-4)

=(x+1)(x+3)(x+4)(x-1)

(2)

=(x^2+4-4x)(x^2+4+4x)

=(x-2)^2(x+2)^2

(3)

=(x-2)(x^2+2x+4)

(4)

(x-3)^2+(y+4)^2=0

x=3,y=-4

x-3y=3+12=15

(5)

=199+195+191+187+...+11+7+1

=(199+1)*50/2

=5000