plz help me ans the question.I need the steep,,thz!
1)The cost of employing workers and buying materials for the renewing of a flat are $10000 and $6000respectively.If the cost employing workers is decreased by 10% and that for buying the materials is increased by 30%,what is the percentage change of cost for renewing this flat?
2)If 12x^2+13x+3 can be factorized into (3x+1)(ax+3),find the value of a.
3)If P=2x+3 and Q=1-X,then P^2-Q^2=?
f.3 mathz!!!
2008-10-23 7:53 pm
回答 (3)
2008-10-27 8:36 pm
1) percentage change= new value - orginal value x100%
orignal value
(10000 x (1-10%) )x (6000 x (1+30%)) - (10000 x 6000) x100%
10000 x 6000
= ((70 200 000-60 000 000)/60 000 000) x100%
= 17%
2) 12x^2+13x+3 = (3x+1)(ax+3)
24x+13x+3 = (3x+1)(ax+3)
37x+3 = (3x+1)(ax+3)
(3x+1)(12.33...x+3) = (3x+1)(ax+3)
a=12.33...
=37/3
3) P=2x+3
Q=1-X
P^2-Q^2
=(2x+3)2 - (1-x)2
=(2x+3)(2x+3) - (1-x)(1-x)
=(4x2+6x+6x+9) - (1-x2-x2+x2)
=(4x2+12x+9) - (1-2x2+x2)
=4x2+12x+9-1+2x2-x2
=5x2+12x+8
orignal value
(10000 x (1-10%) )x (6000 x (1+30%)) - (10000 x 6000) x100%
10000 x 6000
= ((70 200 000-60 000 000)/60 000 000) x100%
= 17%
2) 12x^2+13x+3 = (3x+1)(ax+3)
24x+13x+3 = (3x+1)(ax+3)
37x+3 = (3x+1)(ax+3)
(3x+1)(12.33...x+3) = (3x+1)(ax+3)
a=12.33...
=37/3
3) P=2x+3
Q=1-X
P^2-Q^2
=(2x+3)2 - (1-x)2
=(2x+3)(2x+3) - (1-x)(1-x)
=(4x2+6x+6x+9) - (1-x2-x2+x2)
=(4x2+12x+9) - (1-2x2+x2)
=4x2+12x+9-1+2x2-x2
=5x2+12x+8
2008-10-27 8:18 pm
1) old cost=$10000+$6000=$16000
new cost=$10000*(1-10%)+$6000*(1+30%)=$16800
percentage change=($16800-$16000)/$16000*100%=5%
Therefore, the cost has been increased by 5%.
2) (3x+1)(ax+3)
=3ax^2+(9+a)x+3
therefore 3a=12 and 9+a=13
by induction, a=4
3) P^2-Q^2
=(P+Q)(P-Q)
=((2x+3)+(1-x))((2x+3)-(1-x))
=(2x+3+1-x)(2x+3-1+x)
=(x+4)(3x+2)
=3x^2+14x+8
new cost=$10000*(1-10%)+$6000*(1+30%)=$16800
percentage change=($16800-$16000)/$16000*100%=5%
Therefore, the cost has been increased by 5%.
2) (3x+1)(ax+3)
=3ax^2+(9+a)x+3
therefore 3a=12 and 9+a=13
by induction, a=4
3) P^2-Q^2
=(P+Q)(P-Q)
=((2x+3)+(1-x))((2x+3)-(1-x))
=(2x+3+1-x)(2x+3-1+x)
=(x+4)(3x+2)
=3x^2+14x+8
2008-10-27 8:13 pm
1) $10000 x (1-10%) = $9000 (decreased by 10% )
$6000 x (1+30%) = $7800 (increased by 30%)
9000+7800=$16800
.
. . 16800-16000
--------------- = 5% (increased by 5%)
16000
$6000 x (1+30%) = $7800 (increased by 30%)
9000+7800=$16800
.
. . 16800-16000
--------------- = 5% (increased by 5%)
16000
收錄日期: 2021-04-13 16:11:40
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081023000051KK00526