1.已知a/2=b/3=c/4,且2a+b+c=33,求a,b,c的值2.已知x/4=y/5=z/6,求(x-y+3z)/(3x+2y)的值3.小明家承包了两块三角形地△ABC和△A'B'C',已知AB/A'B'=BC/B'C'=AC/A'C'=3/4.且△ABC的周长为120米,你能求出△A'B'C'这块地的周长
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/09 05:57:37
![1.已知a/2=b/3=c/4,且2a+b+c=33,求a,b,c的值2.已知x/4=y/5=z/6,求(x-y+3z)/(3x+2y)的值3.小明家承包了两块三角形地△ABC和△A'B'C',已知AB/A'B'=BC/B'C'=AC/A'C'=3/4.且△ABC的周长为120米,你能求出△A'B'C'这块地的周长](/uploads/image/z/3756424-40-4.jpg?t=1.%E5%B7%B2%E7%9F%A5a%2F2%3Db%2F3%3Dc%2F4%2C%E4%B8%942a%2Bb%2Bc%3D33%2C%E6%B1%82a%2Cb%2Cc%E7%9A%84%E5%80%BC2.%E5%B7%B2%E7%9F%A5x%2F4%3Dy%2F5%3Dz%2F6%2C%E6%B1%82%28x-y%2B3z%29%2F%283x%2B2y%29%E7%9A%84%E5%80%BC3.%E5%B0%8F%E6%98%8E%E5%AE%B6%E6%89%BF%E5%8C%85%E4%BA%86%E4%B8%A4%E5%9D%97%E4%B8%89%E8%A7%92%E5%BD%A2%E5%9C%B0%E2%96%B3ABC%E5%92%8C%E2%96%B3A%27B%27C%27%2C%E5%B7%B2%E7%9F%A5AB%2FA%27B%27%3DBC%2FB%27C%27%3DAC%2FA%27C%27%3D3%2F4.%E4%B8%94%E2%96%B3ABC%E7%9A%84%E5%91%A8%E9%95%BF%E4%B8%BA120%E7%B1%B3%2C%E4%BD%A0%E8%83%BD%E6%B1%82%E5%87%BA%E2%96%B3A%27B%27C%27%E8%BF%99%E5%9D%97%E5%9C%B0%E7%9A%84%E5%91%A8%E9%95%BF)
1.已知a/2=b/3=c/4,且2a+b+c=33,求a,b,c的值2.已知x/4=y/5=z/6,求(x-y+3z)/(3x+2y)的值3.小明家承包了两块三角形地△ABC和△A'B'C',已知AB/A'B'=BC/B'C'=AC/A'C'=3/4.且△ABC的周长为120米,你能求出△A'B'C'这块地的周长
1.已知a/2=b/3=c/4,且2a+b+c=33,求a,b,c的值
2.已知x/4=y/5=z/6,求(x-y+3z)/(3x+2y)的值
3.小明家承包了两块三角形地△ABC和△A'B'C',已知AB/A'B'=BC/B'C'=AC/A'C'=3/4.且△ABC的周长为120米,你能求出△A'B'C'这块地的周长吗?
4.如果a/b=(a-c)/(c-b)且abc≠0,则等式1/a+1/b=2/c成立吗?为什么?
1.已知a/2=b/3=c/4,且2a+b+c=33,求a,b,c的值2.已知x/4=y/5=z/6,求(x-y+3z)/(3x+2y)的值3.小明家承包了两块三角形地△ABC和△A'B'C',已知AB/A'B'=BC/B'C'=AC/A'C'=3/4.且△ABC的周长为120米,你能求出△A'B'C'这块地的周长
1,令a/2=b/3=c/4=k,则a=2k,b=3k,c=4k,所以2a+b+c=2*2k+3k+4k=11k=33,所以k=3,因此a=6,b=9,c=12
2题的解法和一题一样.
3题周长比等于边长比,所以△A'B'C'得周长为160米.
4题成立,因为由分式得a(c-b)=b(a-c),所以c(a+b)=2ab,所以2/c=(a+b)/ab=1/a+1/b
1.a=6,b=9,c=12
2.特殊值法,令x=4,y=5,z=6 可得结果:17/22
3.120/x=3/4 => x=160
4.成立;a/b=(a-c)/(c-b) =>a/b=(a+a-c)/(b+c-b) 即 a/b=(2a-c)/c
=> 2ab-bc=ac => 2ab=c(b+a) => (a+b)/ab=2/c =>1/a+1/b=2/c
1.a=2k b=3k c=4k代入4k+3k+4k=33 得k=3 a=6 b=9 c=12
2.如上题设k再代入