急---2條數學[F.2 simplify]

分子和分母有點混亂, 現在讓我替你加上括號, 嘗試找出答案。如果我誤解了你的意思, 請再提出問題。

1) 應該是兩個分數相減, 對嗎 ?　　先通分找出公分母 3( w + 2 )
( 7w – 10 ) / [ 3( w + 2 ) ] – 4w / ( 2 + w )
= ( 7w – 10 ) / [ 3( w + 2 ) ] – 4w / ( w + 2 )
= ( 7w – 10 ) / [ 3( w + 2 ) ] – 12w / [ 3( w + 2 ) ]
= [ ( 7w – 10 ) – 12w ] / [ 3( w + 2 ) ]
= ( 7w – 10 – 12w ) / [ 3( w + 2 ) ]
= (–5w – 10 ) / [ 3( w + 2 ) ]
= –5( w + 2 ) / [ 3( w + 2 ) ]
= –5 / 3

2) 應該是三個分數相加, 對嗎 ?　　先通分找出公分母 6( x – 1 )
( 8x + 13) / [ 3( x – 1 ) ] + 3( 2x + 3 ) / [ 2( 1 – x ) ] + x / [ 2( x – 1 ) ]
= ( 8x + 13 ) / [ 3( x – 1 ) ] – 3( 2x + 3 ) / [ 2( x – 1 ) ] + x / [ 2( x – 1 ) ]
= 2( 8x + 13 ) / [ 6( x – 1 ) ] – 9( 2x + 3 ) / [ 6( x – 1 ) ] + 3x / [ 6( x – 1 ) ]
= [ 2( 8x + 13 ) – 9( 2x + 3 ) + 3x ] / [ 6( x – 1 ) ]
= [ ( 16x + 26 ) – ( 18x + 27 ) + 3x ] / [ 6( x – 1 ) ]
= ( 16x + 26 – 18x – 27 + 3x ) / [ 6( x – 1 ) ]
= ( x – 1 ) / [ 6( x – 1 ) ]
= 1 / 6

1) 7w-10/3(w+2)-4w/2+w
=7w-10w/3-20/3-2w+w
=(1/3)[8w-20]


2)8x+13/3(x-1) + 3(2x+3)/2(1-x)+x/2(x-1)
=8x+13x/3-13/3+(6x+9)/(2-2x)+x/(2x-2)
=8x+(13x-13)/3+(5x+9)/(2-2x)
=(1/3)(24x+13x-13)+(5x+9)/(2-2x)
=(1/3)(37x-13)+(5x+9)/(2-2x)


我諗應該係甘....

2009-07-26 20:29:17 補充：
1) 7w-10/3(w+2)-4w/2+w
=7w-10/(3w+6)-2w+w
=6w-10/(3w+6)



2)8x+13/3(x-1) + 3(2x+3)/2(1-x)+x/2(x-1)
=8x+13/(3x-3)-(6x+9)/(2x-2)+x/(2x-2)
=8x+[1/(x-1)][13/3-(6x+9)/2+x/2]
=8x+[1/(x-1)][(26-18x-27+3x)/6]
=8x-[1/(x-1)][(1+15x)/6]


um....我認為你打漏括號

1) 7w-10/3(w+2)-4w/2+w
=7w-[10/3(w)]+(20/3)-2w/1+w
=[3/2/3(w)]+(6/2/3)-3w
=[3/2/3(w)]-3w+(6/2/3)
=2/3(w)+(6/2/3)
============
2) 8x+13/3(x-1) + 3(2x+3)/2(1-x)+x/2(x-1)
=8x+13/[3(x)-(13/3)]+(6x+9)/(2-2x)+[x/(2x-2)]
=i don't know...but look like finish!!