2./x/-3./x/+18=/x/
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(8 x 18 -5 x 18 -18 x3) x y + 2 x y =8 x 7 + 2
<=>144 x y -90 x y -54 x y + 2 x y = 58
<=>2 x y = 58
<=> y = 29
Vậy y = 29
Tìm y biết :
(8 x 18 - 5 x 18 - 18 x 3) x y + 2 x y = 8 x 7 + 2
[ 18 x ( 8 - 5 - 3 ) ] x y = 56 + 2
[ 18 x ( 8 - 5 - 3 ) ] x y = 58
( 18 x 0 ) x y = 58
0 x y + 2 x y = 58
2 x y = 58
y = 58 : 2
y = 29
a) 32 : 4 : 2 = 8 : 2 = 4
32 : 4 : 2 = 32 : 2 = 16
b) 18 : 2 x 3 = 18 : 6 = 3
18 : 2 x 3 = 9 x 3 = 18
a) Ta có: \(\dfrac{x-2}{15}+\dfrac{x-3}{14}+\dfrac{x-4}{13}+\dfrac{x-5}{12}=4\)
\(\Leftrightarrow\dfrac{x-2}{15}-1+\dfrac{x-3}{14}-1+\dfrac{x-4}{13}-1+\dfrac{x-5}{12}-1=0\)
\(\Leftrightarrow\dfrac{x-17}{15}+\dfrac{x-17}{14}+\dfrac{x-17}{13}+\dfrac{x-17}{12}=0\)
\(\Leftrightarrow\left(x-17\right)\left(\dfrac{1}{15}+\dfrac{1}{14}+\dfrac{1}{13}+\dfrac{1}{12}\right)=0\)
mà \(\dfrac{1}{15}+\dfrac{1}{14}+\dfrac{1}{13}+\dfrac{1}{12}>0\)
nên x-17=0
hay x=17
Vậy: x=17
b) Ta có: \(\dfrac{x+1}{19}+\dfrac{x+2}{18}+\dfrac{x+3}{17}+...+\dfrac{x+18}{2}+18=0\)
\(\Leftrightarrow\dfrac{x+1}{19}+1+\dfrac{x+2}{18}+1+\dfrac{x+3}{17}+1+...+\dfrac{x+18}{2}+1=0\)
\(\Leftrightarrow\dfrac{x+20}{19}+\dfrac{x+20}{18}+\dfrac{x+20}{17}+...+\dfrac{x+20}{2}=0\)
\(\Leftrightarrow\left(x+20\right)\left(\dfrac{1}{19}+\dfrac{1}{18}+\dfrac{1}{17}+...+\dfrac{1}{2}\right)=0\)
mà \(\dfrac{1}{19}+\dfrac{1}{18}+\dfrac{1}{17}+...+\dfrac{1}{2}>0\)
nên x+20=0
hay x=-20
Vậy: x=-20
\(\frac{1.5.18+2.10.36+3.15.54}{1.3.9+2.6.18+3.9.27}=\frac{1.5.18.\left(1+2.2.2+3.3.3\right)}{1.3.9.\left(1+2.2.2+3.3.3\right)}\)
\(=\frac{1.5.18}{1.3.9}=\frac{10}{3}\)
(8 x 18 -5 x 18 -18 x3) x y + 2 x y =8 x 7 + 2
<=>144 x y -90 x y -54 x y + 2 x y = 58
<=>2 x y = 58
<=> y = 29
vậy y = 29
( mình ko chép lại đề bài đâu nha ,giải lun đó)
[18x(8-5-3)]xy+2xy=56+2
(18x0)xy+2xy=58
0xy+2xy=58
2xy=58
y=58:2=29
tick cho mình nha
5 x 6 = 30 2 x 6 = 12 3 x 6 = 18 4 x 6 = 24
6 x 5 = 30 6 x 2 = 12 6 x 3 = 18 6 x 4 = 24
a, 3.(2\(x\) + 4) + 198 = (-3)2.10
3.(2\(x\) + 4) + 198 = 90
3.(2\(x\) + 4) = 90 - 198
3.(2\(x\) + 4) = - 108
2\(x\) + 4 = -108 : 3
2\(x\) + 4 = -36
2\(x\) = - 36 - 4
2\(x\) = - 40
\(x\) = -40 : 2
\(x\) = - 20
b, 2.(\(x\) + 7) - 6 = 18
2.(\(x\) + 7) = 18 + 6
2.(\(x\) + 7) =24
\(x\) + 7 = 24 : 2
\(x\) + 7 = 12
\(x\) = 12 - 7
\(x\) = 5
\(-\left|x\right|+18=\left|x\right|\)
\(2\left|x\right|=18\)
\(\Rightarrow\left|x\right|=9\)
\(\Rightarrow x=9,x=-9\)
Vậy x thuộc 9;-9.
Học tốt^^
\(-\left|x\right|+18=\left|x\right|\)
\(2\left|x\right|=18\)
\(\Rightarrow\left|x\right|=9\)
\(\Rightarrow x=9,x=-9\)
Vậy x thuộc 9;-9.
Học tốt^^