\(\text{7x- xy+ 2y= 18}\)
\(\Rightarrow xy-2y=7x-18\)
\(\Rightarrow y\left(x-2\right)=7x-18\)
\(\Rightarrow y=\dfrac{7x-18}{x-2}\)
\(=\dfrac{7x-14}{x-2}-\dfrac{4}{x-2}=7-\dfrac{4}{x-2}\)
\(x-2\in U\left(4\right)\) nếu \(y\in Z\)
Nếu x-2 = -2 \(\Rightarrow\) x = 0 ; y = 9
Nếu x-2 = -4 \(\Rightarrow\) x = -2 ; y = 8
Nếu x -2 = 2 \(\Rightarrow\) x = 4 ; y = 5
Nếu x-2 = 1 \(\Rightarrow\) x = 3 ; y = 3
Nếu x-2 = -1\(\Rightarrow\) x = 1 ; y = 11
Nếu x-2 = 4 \(\Rightarrow\) x = 6 ; y = 6
Tìm x bt :
a) x + x - 1 + x - 2 +...+z - 50 = 255
b) \(\left(x-\dfrac{1}{3}\right)^2-\dfrac{1}{4}=0\)
c) -2x + 624 = 5y (x,y \(\in\) N )
d) \(\dfrac{x+5}{2}=\dfrac{8}{x+5}\)
e) x + ( x + 1 ) + ( x + 2 ) +...+ ( x + 30 ) =1240
f) ( x - 1 ) + ( x - 2 ) + ... + (x - 19 ) + ( x - 20 ) = -610
g) ( 7x - 11 )3 = ( -3 )2 . 15 + 208
Tìm các số nguyên x, y thỏa mãn :
a) \(\dfrac{5}{7}-1\dfrac{4}{7}\left(450\%+\dfrac{2}{3}x\right)=-\dfrac{1}{14}\)
b) 100 = 6 .7|x+2| - 194
c) 2x + 3 = y2 ( với x, y \(\in\) N )
1)tìm x\(\in\)Q biết:
a)\(\left(5\cdot x+1\right)^2=\dfrac{36}{49}\)
2)tìm x,y biết:
a)\(x^2+\left(y-\dfrac{1}{10}\right)^4=0\)
b)\(\left(\dfrac{1}{2}x-5\right)^{20}+\left(y^2-\dfrac{1}{4}\right)^{40}\le0\)
Bài 1 : Tìm GTNN
A = \(\left(x-\dfrac{1}{4}\right)^2+\left|y+\dfrac{1}{4}\right|+\dfrac{13}{14}\)
Bài 2 : Tìm x , y là số nguyên
a) \(\dfrac{x+3}{5}-\dfrac{1}{y-1}=\dfrac{2}{5}\)
b) \(-1-\dfrac{7}{14}\le\dfrac{x}{3}\le1+\dfrac{12}{48}\)
c) \(\dfrac{2y+7}{y-2}\in Z\)
giúp mk với 
sáng mai mk có tiết toán
tìm các số nguyên x, y biết
a, \(\dfrac{24}{7x-3}\)=\(\dfrac{-4}{25}\)
b, \(\dfrac{4}{x-6}\)=\(\dfrac{y}{24}\)=\(\dfrac{-12}{18}\)
c, \(\dfrac{-1}{5}\)<\(\dfrac{x}{8}\)<\(\dfrac{1}{4}\)
d, \(\dfrac{x+46}{20}\)=x\(\dfrac{2}{5}\)
f, y\(\dfrac{5}{y}\)=\(\dfrac{86}{y}\)
1)tìm x,y,Z,biết:
a)7x=4y và y-x=24
b)\(\dfrac{x}{5}=\dfrac{y}{6},\dfrac{y}{8}=\dfrac{Z}{7}\)và x+y-z=69
c)\(\dfrac{x}{y}=\dfrac{2}{5}vàx-y=40\)
giúp mình nhé !
tìm x,y và z biết
1) \(\dfrac{x+1}{3}=\dfrac{y+2}{4}=\dfrac{z+3}{5}\) và x + y + z = 18
help me!!!!!!!!!!!!!!!!!!!!!!!!!
Câu 1: Tìm x,y \(\in\) x biết:
\(\dfrac{x-4}{y-3}=\dfrac{4}{3}\) và x-y=5
Câu 2: Tình:
\(B=\dfrac{10}{56}+\dfrac{10}{140}+\dfrac{10}{260}+...+\dfrac{10}{1400}\)
Câu 3: Tìm x biết
38 - ( |x+10|+13)=\(\left(-6\right)^{20}:\left(9^9.4^{10}\right)\)
BT3: Tìm x, biết:
7) \(\dfrac{-5}{17}+\dfrac{3}{17}\le\dfrac{x}{17}\le\dfrac{13}{17}+\dfrac{-11}{17}\)
8) \(\dfrac{2}{3}\left(\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{1}{3}\right)\le\dfrac{x}{18}\le\dfrac{7}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)\)
