Vì (1/3-2x)^102 và (3y-x)104 lớn hơn hoặc bằng 0 với mọi x và y

=>(1/3-2x)^102 và (3y-x)^104=0

Ta có: (1/3-2x)^102=0

=>1/3-2x=0

=>2x=1/3

=>x=1/6

Ta có:(3y-x)^104=0

=>3y-1/6=0

=>3y=1/6

=>y=1/18

Vậy x=1/6 và y=1/18

mu chan => lon hon hoac bang 0 => 1/3-2x = 0, 3y - x=0

Ta có:

\(\left(\frac{1}{3}-2x\right)^{102}+\left(3y-x\right)^{104}=0\left(1\right)\)

Nhận thấy:

\(\left(\frac{1}{3}-2x\right)^{102}\ge0;\left(3y-x\right)^{104}\ge0\forall x,y\)

Do đó (1) xảy ra khi và chỉ khi:

\(\hept{\begin{cases}\frac{1}{3}-2x=0\\3y-x=0\end{cases}\Leftrightarrow}\hept{\begin{cases}x=\frac{1}{6}\\y=\frac{1}{18}\end{cases}}\)

1) \(\Rightarrow\dfrac{x}{8}=\dfrac{y}{12}=\dfrac{z}{15}\)

Áp dụng t/c dtsbn:

\(\dfrac{x}{8}=\dfrac{y}{12}=\dfrac{z}{15}=\dfrac{x-y+z}{8-12+15}=\dfrac{10}{11}\)

\(\Rightarrow\left\{{}\begin{matrix}\dfrac{x}{8}=\dfrac{10}{11}\\\dfrac{y}{12}=\dfrac{10}{11}\\\dfrac{z}{15}=\dfrac{10}{11}\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{80}{11}\\y=\dfrac{120}{11}\\z=\dfrac{150}{11}\end{matrix}\right.\)

2) \(\Rightarrow\left\{{}\begin{matrix}\dfrac{x}{3}=\dfrac{y}{4}\\\dfrac{y}{5}=\dfrac{z}{7}\end{matrix}\right.\) \(\Rightarrow\dfrac{x}{15}=\dfrac{y}{20}=\dfrac{z}{28}\)

Áp dụng t/c dtsbn:

\(\dfrac{x}{15}=\dfrac{y}{20}=\dfrac{z}{28}=\dfrac{2x}{30}=\dfrac{3y}{60}=\dfrac{2x+3y-z}{30+60-28}=\dfrac{136}{62}=\dfrac{68}{31}\)

\(\Rightarrow\left\{{}\begin{matrix}\dfrac{x}{15}=\dfrac{68}{31}\\\dfrac{y}{20}=\dfrac{68}{31}\\\dfrac{z}{28}=\dfrac{68}{31}\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{1020}{31}\\y=\dfrac{1360}{31}\\z=\dfrac{1904}{31}\end{matrix}\right.\)

3) \(\Rightarrow\dfrac{3x-9}{15}=\dfrac{5y-25}{5}=\dfrac{7z+21}{49}\)

Áp dụng t/c dtsbn:

\(\dfrac{3x-9}{15}=\dfrac{5y-25}{5}=\dfrac{7z+21}{49}=\dfrac{3x+5y-7z-9-25-21}{15+5-49}=-\dfrac{45}{29}\)

\(\Rightarrow\left\{{}\begin{matrix}\dfrac{3x-9}{15}=-\dfrac{45}{29}\\\dfrac{5y-25}{5}=-\dfrac{45}{29}\\\dfrac{7z+21}{49}=-\dfrac{45}{29}\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=-\dfrac{138}{29}\\y=\dfrac{100}{29}\\z=-\dfrac{402}{29}\end{matrix}\right.\)

x=100

Ta sẽ có: 1-1+1+1-1+1-1+1=0

\(\frac{x-1}{99}-\frac{x+1}{101}+\frac{x-2}{98}-\frac{x+2}{102}+\frac{x-3}{97}-\frac{x+3}{103}+\frac{x-4}{96}-\frac{x+4}{104}=0\)

\(\Rightarrow\frac{x-1}{99}-1-\frac{x+1}{101}+1+\frac{x-2}{98}-1-\frac{x+2}{102}+1+\frac{x-3}{97}-1-\frac{x+3}{103}+1+\frac{x-4}{96}-1-\frac{x+4}{104}+1=0\)

\(\Rightarrow\frac{x-100}{99}-\frac{x-100}{101}+\frac{x-100}{98}-\frac{x-100}{102}+\frac{x-100}{97}-\frac{x-100}{103}+\frac{x-100}{96}-\frac{x-100}{104}=0\)

\(\Rightarrow\left(x-100\right).\left(\frac{1}{99}-\frac{1}{101}+\frac{1}{98}-\frac{1}{102}+\frac{1}{97}-\frac{1}{103}+\frac{1}{96}-\frac{1}{104}\right)=0\)

Vì \(\frac{1}{99}>\frac{1}{101};\frac{1}{98}>\frac{1}{102};\frac{1}{97}>\frac{1}{103};\frac{1}{96}>\frac{1}{104}\)

\(\Rightarrow\frac{1}{99}-\frac{1}{101}+\frac{1}{98}-\frac{1}{102}+\frac{1}{97}-\frac{1}{103}+\frac{1}{96}-\frac{1}{104}\ne0\)

\(\Rightarrow x-100=0\)

\(\Rightarrow x=100\)

Vậy \(x=100\)

x thuoc R

\(\dfrac{x-1}{99}-\dfrac{x+1}{101}+\dfrac{x-2}{98}-\dfrac{x+2}{102}+\dfrac{x-3}{97}-\dfrac{x+3}{103}+\dfrac{x-4}{96}-\dfrac{x+4}{104}=0\)
<=> \(\dfrac{x-1}{99}-1-\dfrac{x+1}{101}-1+\dfrac{x-2}{98}-1-\dfrac{x-2}{102}-1+\dfrac{x-3}{97}-1-\dfrac{x+3}{103}-1+\dfrac{x-4}{96}-1-\dfrac{x+4}{104}=0\)

9092 = 0

cái này + mỗi phân số vs 1 á 

gặp mấy dạng này + hoặc - cho 1 số nào đó là giải đc , bn tự lm xem

a) |x+1|+|x+5|=4

\(\Rightarrow x+1+x+5=\pm4\)

\(x+1+x+5=4\)

\(\Rightarrow x^2+1+5=4\)

\(x^2+6=4\)

\(x^2=4-6\)

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

\(x+1+x+5=-4\)

\(x^2+6=-4\)

\(x^2=-8\)

a) trường hợp 1:x\(\ge\)-1

x+1+x+5=4\(\Rightarrow2x+6=4\Rightarrow x=-1\)(TM)

TH2:\(-5\le x< -1\)

-x-1+x+5=4(phương trình vô nghiệm)

TH3:x<-5

-x-1-x-5=4\(\Rightarrow-2x-6=4\Rightarrow-5\)(KTM)

vậy x=-1

b)

b: Ta có: \(\left|2x-1\right|\ge0\forall x\)

\(\left|x-3y\right|\ge0\forall x,y\)

Do đó: \(\left|2x-1\right|+\left|x-3y\right|\ge0\forall x,y\)

Dấu '=' xảy ra khi \(\left(x,y\right)=\left(\dfrac{1}{2};\dfrac{1}{6}\right)\)