Question

急需!因式分解(1)a(a+b)-5(a+b)；(2)(a+b)-(a+b)²；（3）x(x-y)+y(y-x

Answer 1

a( a + b ) - 5( a + b )

= ( a + b )( a - 5 )

( a + b ) - ( a + b )"

= ( a + b )( 1 - a - b )

x( x - y ) + y( y - x ) + x - y

= x( x - y ) - y( x - y ) + ( x - y )

= ( x - y )( x - y + 1 )

m"n - mn"

= mn( m - n )

= ( -1 )X 3

= -3

2x"( y + 3 ) - 4x( y + 3 )

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

= ( 2X2 )( -10 + 3 )( 2 - 2 )

= 0

a"' - 8a" + 16a

= a( a" - 8a + 16 )

= a( a - 4 )"

第六题注意,没有分数线,就要加括号

( 2007"' - 2X2007" - 2005 ) / ( 2007"' + 2007" - 2008 )

先看分母

2007"' + 2007" - 2008

= 2007"' - 1 + 2007" - 2007

= ( 2007 - 1 )( 2007" + 2007 + 1 ) + 2007( 2007 - 1 )

= ( 2007 - 1 )( 2007" + 2X2007 + 1 )

= 2006 X ( 2007 + 1 )"

= 2006 X 2008"

再看分子

2007"' - 2X2007" - 2005

= 2007"( 2007 - 2 ) - ( 2007 - 2 )

= ( 2007 - 2 )( 2007" - 1 )

= 2005X( 2007 - 1 )( 2007 + 1 )

= 2005 X 2006 X 2008

结果就是

( 2005 X 2006 X 2008 ) / ( 2006 X 2008" )

= 2005 / 2008