Question

初一数学题 因式分解

-9x^2+y^2
(x-y)^2-10(y-x)+25
(m+n)^2+10(m+n)+25
(a+b)^2-100
4(a+2b)^2-36(a-b)^2
1.25x14^2-125x8.6^2
要过程

Answer 1

-9x^2+y^2=y^2-9x^2
=(y-3x)(y+3x)

(x-y)^2-10(y-x)+25
=(x-y)^2+10(x-y)+25
=(x-y+5)^2

(m+n)^2+10(m+n)+25
=(m+n+5)^2

(a+b)^2-100
=(a+b)^2-10^2
=(a+b+10)(a+b-10)

4(a+2b)^2-36(a-b)^2
=[2(a+2b)]^2-[9(a-b)]^2
={[2(a+2b)]+[9(a-b)]}{[2(a+2b)]-[9(a-b)]}
=(13a-5b)(13b-5a)

1.25x14^2-125x8.6^2
=5(0.25x14^2-25x8.6^2)
=5(0.5x14-5x8.6)(0.5x14+5x8.6)
=5(7-43)(7+43)

Answer 2

-9x^2+y^2=y^2-（3X）^2=(Y-3X)^2

(x-y)^2-10(y-x)+25=(y-X)^2-2*5(y-x)+5^2=(y-x-5)^2

(m+n)^2+10(m+n)+25=(m+n)^2+2*5（m+n）+5^2=（m+n+5）^2

(a+b)^2-100=(a+b)^2-10^2=（a+b+10)(a+b-10)

4(a+2b)^2-36(a-b)^2=[2(a+2b)]^2-[6(a-b)]^2
=[2(a+2b)+6(a-b)][2(a+2b)-6(a-b)]
=(8a-2b)(10b-4a)
=4(4a-b)(5b-2a)

1.25x14^2-125x8.6^2=1.25x14^2-1.25x(10x8.6)^2
=1.25x[14^2-86^2]
=1.25x(14+86)(14-86)
=1.25x100x(-72)
=-9000

Answer 3

(y-3x)(y+3x)
(x-y-5)^2
(m+n+5)^2
(a+b-10)(a+b+10)
(2a+4b-6a+6b)(2a+4b+6a-6b)=(10b-2a)(8a-2b)
1.25 (14-86)(14+86)=1.25X(-72)X100=-9000

追问

-9x^2+y^2

(a+b)^2-100这两道题的过程

Answer 4

1.    (Y-3X)(Y+3X)

2.    (X-Y+5)^2

3.   (m+n+5)^2

4.    (a+b+10)(a+b-10)

5.   (10b-4a)(8a-2b)

6.  -9000
   

追问

-9x^2+y^2

(a+b)^2-100这两道题的过程

追答

-9x^2+y^2=y^2-9x^2 =(y-3x)(y+3x)

(a+b)^2-100=(a+b)^2-10^2=（a+b+10)(a+b-10)

Answer 5

第一个是不是漏了？