Tìm các số nguyên x và y biết được là 7/x = y/27 = -42/54
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
7/x=y/27=-42/54=-7/9
7/x=-7/9 nên x=-9
y/27=-7/9=-21/27 nên y=-21
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
![](https://rs.olm.vn/images/avt/0.png?1311)
`A)2/3=x/60`
`=>40/60=x/60`
`=>x=40`
`B)-1/2=y/18`
`=>-9/18=y/18`
`=>y=-9`
`C)3/x=y/35=-36/84`
Mà `-36/84=(-3 xx 12)/(7 xx 12)=-3/7`
`=>3/x=-3/7`
`=>x=-7`
`y/35=-3/7=-15/35`
`=>y=-15`
`D)7/x=y/27=-42/54`
Mà `-42/54=(-7 xx 6)/(9 xx 6)=-7/9`
`=>7/x=-7/9`
`=>x=-9`
`y/27=-7/9=-21/27`
`=>y=-21`
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{7}{x}=\frac{y}{27}=\frac{-42}{54}\)
+) => \(\frac{y\cdot2}{27\cdot2}=\frac{-42}{54}\)
=> \(y\cdot2=-42\)
\(\Rightarrow y=-21\)
+) \(\frac{7}{x}=\frac{-21}{27}\)
=> \(\frac{7\cdot\left(-3\right)}{x\cdot\left(-3\right)}=\frac{-21}{27}\)
=> \(x\cdot\left(-3\right)=27\)
=> \(x=-9\)
* Lớp 6 chưa học đến tỉ lệ thức nên đây là cách đơn giản nhất r *
\(\frac{y}{27}\)=\(\frac{-42}{54}\)=>\(\frac{2y}{54}\)=\(\frac{-42}{54}\)=>2y= -42 y= \(\frac{-42}{2}\)= -21 \(\frac{7}{x}\)=\(\frac{-21}{27}\)=> -21x=7*27=189 x=\(\frac{189}{-21}\)= -9 Vậy x= -9, y= -21
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{7}{x}=\frac{y}{21}=\frac{-42}{54}\)
Ta có : \(\frac{-42}{54}=\frac{-42:6}{54:6}=\frac{-7}{9}\)
+) \(\frac{7}{x}=\frac{-7}{9}\)=> 7.9 = (-7).x => (-7).x = 63 => x = -9
+) \(\frac{y}{21}=\frac{-7}{9}\)=> y.9 = 21.(-7) => y.9 = -147 => y = -49/3
Vậy x = 9,y = -49/3
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có
7/x = -42/54 => x= 7.54/-42 =>x=-9 (tmđk)
y/21 = -42/54 => y= -42.21/54 => y= -49/3
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{4}{x}=\dfrac{y}{21}=\dfrac{28}{49}=\dfrac{28:7}{49:7}=\dfrac{4}{9}\\ Vậy:x=\dfrac{4.9}{4}=9\\ y=\dfrac{4.21}{9}=\dfrac{28}{3}\)
\(\dfrac{x}{2}=\dfrac{3}{y}\\ \Leftrightarrow x.y=2.3=6\\ Vậy:\left[{}\begin{matrix}\left(x;y\right)=\left(1;6\right)=\left(6;1\right)\\\left(x;y\right)=\left(2;3\right)=\left(3;2\right)\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
\(\frac{y}{27}=\frac{-42}{54}\)
\(\Rightarrow y=\frac{-42.27}{54}=-21\)
Lại có:
\(\frac{7}{x}=\frac{-21}{27}\)
\(\Rightarrow x=\frac{7.27}{-21}=-9\)
Vậy .....
Tìm x:
\(\frac{7}{x}\)= \(\frac{-42}{54}\)
\(\Rightarrow\)\(\frac{7.\left(-6\right)}{x.\left(-6\right)}\) = \(\frac{-42}{54}\)
\(\Rightarrow\)\(x.\left(-6\right)=54\)
\(\Rightarrow x=54\div\left(-6\right)\)
\(\Rightarrow x=-9\)
Tìm y:
\(\frac{y}{27}=\frac{-42}{54}\)
\(\Rightarrow\frac{y.2}{27.2}=\frac{-42}{54}\)
\(\Rightarrow y.2=-42\)
\(\Rightarrow y=\left(-42\right)\div2\)
\(\Rightarrow y=-21\)
\(Họctốtnhé\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (x+5)+(x+10)+.........+(x+60)=450
12x +(5+10+.........+60)=450
12x+390=450
12x=60
x=5
b) Gọi n là thương của phép chia a cho 54; =>54n+38=252+r =>r-2 chia hết cho 54
r là dư của phép chia a cho 18 (n,r thuộc N;r<14) =>54n =214+r =>r-2=0
=>a=54n + 38 =>n=(214+r):54 =>r =2
a=18x14+r =>214+r chia hết cho 54 =>a=18x14+2=254
=>54n+38=18x14+r =>216+r-2 chia hết cho 54
\(\frac{7}{-9}=\frac{-21}{27}=\frac{-42}{54}\)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv