設f(x)+g(x)=5x-6,f(x)-g(x)=x 10則f(3)+g(-3)=?
回答 (2)
2016-05-15 4:11 am
f(x)+g(x)=5x－6 i
f(x)－g(x)=x+10 ii
i+ii
2f(x)=6x+4
f(x)=3x+2
(3x+2)+g(x)=5x-6
g(x)=2x-8
f(3)+g(-3)
=3(3)+2+2(-3)-8
=-3
f(x)－g(x)=x+10 ii
i+ii
2f(x)=6x+4
f(x)=3x+2
(3x+2)+g(x)=5x-6
g(x)=2x-8
f(3)+g(-3)
=3(3)+2+2(-3)-8
=-3
2016-05-15 2:45 am
設f(x)+g(x)=5x－6，f(x)－g(x)=x+10則f(3)+g(－3)=?
Sol
f(x)+g(x)=5x－6
f(x)－g(x)=x+10
[f(x)+g(x)]+[f(x)－g(x)]=(5x－6)+(x+10)
2f(x)=6x+4
f(x)=3x+2
g(x)=(5x－6)－(3x+2)=2x－8
f(3)+g(－3)
=(3*3+2)+[2*(－3)－8]
=11－14
=－3
Sol
f(x)+g(x)=5x－6
f(x)－g(x)=x+10
[f(x)+g(x)]+[f(x)－g(x)]=(5x－6)+(x+10)
2f(x)=6x+4
f(x)=3x+2
g(x)=(5x－6)－(3x+2)=2x－8
f(3)+g(－3)
=(3*3+2)+[2*(－3)－8]
=11－14
=－3
收錄日期: 2021-04-18 14:50:22
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160514183056AAYqict