THeo t/ c dãy tỉ số..

=>7x+2-(7x-1)/5x+7-(5x+1)

=7x+2-7x+1/5x+7-5x-1=3/6=1/2

=>(7x+2).2=5x+7

=>14x+4=5x+7

=>14x-5x=7-4

=>9x=3=>x=1/3

ảnh đẹp đó bạn

Chờ chút,giải lại cho

x=1/3 nhé bạn

tick tớ nhé

tick tớ đi buồn quá nãy giờ chưa ai tick.coi như giúp tớ đi

nhân từng vế 2 tỉ số,phá ngoặc ta được x=1/3=0,(3)

7x + 2 = 7x-1 va 5x+7=5x+1 la pt vo nghiem

Ai giúp mình với. Mình tích cho ạ

Ta có : 

\(\frac{7x+2}{5x+7}=\frac{7x-1}{5x+1}\)

\(=>\left(7x+2\right)\left(5x+1\right)=\left(7x-1\right)\left(5x+7\right)\)

\(=>35x^2+7x+10x+2=35x^2+49x-5x-7\)

\(=>35x^2+17x+2=35x^2+44x-7\)

\(=>17x+2=44x-7\)

\(=>44x-17x=2+7\)

\(=>27x=9\)

\(=>x=\frac{9}{27}=\frac{1}{3}\)

A

\(\frac{7x-12}{5x-2}=\frac{9-7x}{-5x+1}\)

\(=>\frac{2x-10}{5x-2}+1=\frac{-7x+9}{-5x+1}=\frac{-2x+8}{-5x+1}+1\)

\(=>\frac{2x-10}{5x-2}=\frac{-2x+8}{-5x+1}=\frac{-\left(2x-8\right)}{-\left(5x-1\right)}=\frac{2x-8}{5x-1}\)

\(=>\frac{2x-10}{5x-2}=\frac{2x-8}{5x-1}\)

\(=>\frac{5x-1}{5x-2}=\frac{2x-8}{2x-10}\)

\(=>\frac{-1}{5x-2}=\frac{-2}{2x-10}\)

\(=>-2x+10=-10x+4\)

\(=>-2x+10x=4-10=-6\)

\(=>8x=-6\)

\(=>x=\frac{-6}{8}=\frac{-3}{4}\)

P/s ko chắc :v

Ta có: \(\frac{7x-12}{5x-2}=\frac{7x-9}{5x-1}\)

     \(\Rightarrow\left(7x-12\right).\left(5x-1\right)=\left(7x-9\right).\left(5x-2\right)\)

    \(\Leftrightarrow35x^2-7x-60x+12=35x^2-14x-45x+18\)

    \(\Leftrightarrow\left(35x^2-35x^2\right)-\left(7x+60x-14x-45x\right)=18-12\)

    \(\Leftrightarrow8x=6\)

    \(\Leftrightarrow x=\frac{3}{4}\)

Vậy \(\Leftrightarrow x=\frac{3}{4}\)

\(\frac{7x-12}{5x-2}=\frac{9-7x}{-5x+1}\)

\(\left(7x-12\right)\left(-5x+1\right)=\left(9-7x\right)\left(5x-2\right)\)

\(-35x^2+7x+60x-12=45x-18-35x^2+14x\)

\(67x-12=59x-18\)

\(67x-12-59x=18\)

\(8x-12=-18\)

\(8x=-18+12\)

\(8x=-6\)

\(x=-\frac{6}{8}=-\frac{3}{4}\)

\(x=\frac{1}{3}\)

\(7x^2\left(x^2-5x+2\right)-5x\left(x^3-7x^2+3x\right)\)

\(=7x^4-35x^3+14x^2-5x^4+35x^3-15x^2\)

\(=2x^4-x^2\)

Thay: \(x=-\frac{1}{2}\) vào được

\(2.\left(-\frac{1}{2}\right)^4-\left(-\frac{1}{2}\right)^2\)

\(=2.\frac{1}{16}-\frac{1}{4}\)

\(=\frac{1}{8}-\frac{1}{4}=\frac{1}{8}-\frac{2}{8}=-\frac{1}{8}\)

P/s: Ko chắc