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Nhác rồi :(
Dễ thấy GTTĐ ko âm nên:
5x ko âm => x ko âm
=> /x/+/x+1/+/x+2/+/x+3/=x+1+x+2+x+3+x=4x+6=5x=>x=6
Vậy: x=6
a) \(\dfrac{x}{12}=\dfrac{6}{9}\)
\(\Rightarrow x=\dfrac{12\cdot6}{9}=8\)
b) \(\dfrac{9}{15}=x+\dfrac{11}{35}\)
\(\Rightarrow x=\dfrac{9}{15}-\dfrac{11}{35}\)
\(\Rightarrow x=\dfrac{2}{7}\)
c) \(x+\dfrac{6}{5}=\dfrac{x}{2}\)
\(\Rightarrow2\left(x+\dfrac{6}{5}\right)=x\)
\(\Rightarrow2x+\dfrac{12}{5}=x\)
\(\Rightarrow2x-x=-\dfrac{12}{5}\)
\(\Rightarrow x=-\dfrac{12}{5}\)
\(a,\dfrac{x}{12}=\dfrac{6}{9}\\ \Leftrightarrow x=12\cdot\dfrac{6}{9}\\ \Leftrightarrow x=8\\ b,\dfrac{9}{15}=x+\dfrac{11}{35}\\ \Leftrightarrow x=\dfrac{9}{15}-\dfrac{11}{35}\\ \Leftrightarrow x=\dfrac{2}{7}\\ c,x+\dfrac{6}{5}=\dfrac{x}{2}\\ \Leftrightarrow\dfrac{x}{2}=-\dfrac{6}{5}\\ \Leftrightarrow x=-\dfrac{12}{5}\)
Ta có :\(x+2x+3x+...+9x=459-9\)
\(\Rightarrow\)\(x\left(1+2+3+...+9\right)=450\)
\(\frac{\Rightarrow x.\left[\left(9-1\right):1+1\right].\left(9+1\right)}{2}\)\(=450\)
\(\frac{\Rightarrow x.90}{2}=450\)
\(\Rightarrow x.90=450.2=900\)
\(\Rightarrow x=\frac{900}{90}\)
\(\Rightarrow x=10\)
\(\text{Tìm }x\text{ : }\)
\(\text{Ta có : }\)
\(x+2x+3x+...+9x=459-9\)
\(\Rightarrow\text{ }x+2x+3x+...+9x=450\)
\(\Rightarrow\text{ }x\cdot\left(\left(9-1\right)\text{ : }1+1\right)\cdot\left(\left(9+1\right)\text{ : }2\right)=450\)
\(\Rightarrow\text{ }x\cdot\left(8\text{ : }1+1\right)\cdot\left(\left(9+1\right)\text{ : }2\right)=450\)
\(\Rightarrow\text{ }x\cdot\left(8+1\right)\cdot\left(\left(9+1\right)\text{ : }2\right)=450\)
\(\Rightarrow\text{ }x\cdot9\cdot\left(\left(9+1\right)\text{ : }2\right)=450\)
\(x\cdot9\cdot\left(10\text{ : }2\right)=450\)
\(x\cdot9\cdot5=450\)
\(x\cdot45=450\)
\(x=450\text{ : }45\)
\(x=10\)
a) x = 4
b) x = -8
c) | x | - 9 = -2 + 17
| x | = 15 + 9
| x | = 24
x = 24 hoặc x = -24
d) |x – 9| = -2 + 17
|x – 9| = 15
x – 9 = 15 hoặc x – 9 = -15
x = 24 hoặc x = -6
Lời giải:
ĐKXĐ: $x\neq 2$
$\frac{x-2}{-4}=\frac{9}{2-x}$
$\Rightarrow (x-2)(2-x)=(-4).9$
$\Leftrightarrow (x-2)^2=36=6^2=(-6)^2$
$\Leftrightarrow x-2=6$ hoặc $x-2=-6$
$\Leftrightarrow x=8$ hoặc $x=-4$
Bài làm
( 3 + 6 + x ) . 9 = ( 2 - x ) . 2
27 + 54 + 9x = 4 - 2x
9x + 2x = 4 - 27 - 54
11x = -77
x = -7
Vậy x = -7
b) ( 6 - x ) . 3 = ( 9 + x ) . 3
18 - 3x = 27 + 3x
-3x - 3x = 27 - 18
-6x = 9
x = 9/-6
x = -3/2
Vậy x = -3/2
a,\(\text{(3+6+x) . 9 = (2-x).2}\)
\(27+54+9x=4-2x\)
\(9x+2x=4-54-27\)
\(11x=-77\)
\(\Rightarrow x=-7\)
b, \(\text{(6-x) . 3 = (9+x) . 3}\)
\(18-3x=27+3x\)
\(-3x-3x=27-18\)
\(-6x=9\)
\(\Rightarrow x=\frac{9}{-6}\)
học tốt
\(\frac{1.5.18+2.10.36+3.15.54}{1.3.9+2.6.18+3.9.27}=\frac{1.5.18.\left(1+2.2.2+3.3.3\right)}{1.3.9.\left(1+2.2.2+3.3.3\right)}\)
\(=\frac{1.5.18}{1.3.9}=\frac{10}{3}\)
ta có:x+9=(x+2)+7
lại có:(x+2)⋮(x+2)
để(x+9)⋮(x+2) thì 7⋮(x+2)
⇒(x+2)ϵ Ư(7)
mà Ư (7)={1;7}
vậy xϵ(5)