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( 2 x y + 2/15 ) x 3 = 4/5
( 2 x y + 2/15 ) = 4/5 : 3
( 2 x y + 2/15 ) = 4/15
2 x y = 4/15 - 2/15
2 x y = 2/15
y = 2/15 :2
y = 1/15
(2 x y + 2/15) x 3 = 4/5
2 x y + 2/15) = 4/5 : 3
2 x y + 2/15 = 4/15
2 x y = 4/15 - 2/15
2 x y = 2/15
y = 2/15 : 2
y = 1/15
7/9 x (2 - 1/3 x y) = 14/15
(2 - 1/3 x y) = 14/15 : 7/9
(2 - 1/3 x y) = 6/5
2 - y = 6/5 x 1/3
2 - y = 2/5
y = 2/5 + 2
y = 12/5
4/21 + 5 x y - 8/7 = 1/3
4/21 + 5 x y = 1/3 + 8/7
4/21 + 5 x y = 31/21
5 x y = 31/21 - 4/21
5 x y = 9/7
y = 9/7 : 5
y = 9/35
7/12 x y - 3/12 x y = 5
y x (7/12 - 3/12) = 5
y x 1/3 = 5
y = 5 : 1/3
y = 15
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áp dung tc cua day ti so bang nhau co
\(\frac{x}{2}=\frac{y}{3}=\frac{x+y}{2+3}=\frac{-15}{5}=-3\)
x=-6;y=-9
y b lam tuong tuu nhung thay cong bang tru
y c
co \(\frac{x}{y}=\frac{7}{-9}\Rightarrow\frac{x}{7}=\frac{y}{-9}\Rightarrow\frac{2x}{14}=\frac{3y}{-27}\)
lam tuong tuu y a
d,
h cheo
7 ( x + 4 ) = 4 ( 7 + y )
7x + 28 = 4y + 28
7x = 4y
\(\Rightarrow\frac{x}{4}=\frac{y}{7}\)
ap dung tc cua day ti so bang nhau va lam tuong tuu y a
t i c k nha
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\(\dfrac{8}{9}\) : ( 2 - 3 \(\times\) y) = \(\dfrac{5}{3}\)
2 - 3 \(\times\) y = \(\dfrac{8}{9}\) : \(\dfrac{5}{3}\)
2 - 3 \(\times\) y = \(\dfrac{8}{15}\)
3 \(\times\) y = 2 - \(\dfrac{8}{15}\)
3 \(\times\) y = \(\dfrac{22}{15}\)
y = \(\dfrac{22}{15}\) : 3
y = \(\dfrac{22}{45}\)
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x+3}{8}=\dfrac{y-9}{7}=\dfrac{x-y+3+9}{8-7}=\dfrac{-14+17}{1}=3\)
Do đó: x+3=24; y-9=21
=>x=21; y=30