\(15 + ( x + 2 )^2 : 3 =18\)
15 + (x+2)2 :3= 18
\(15+\left(x+2\right)^2:3=18\)
\(\left(x+2\right)^2:3=18-15\)
\(\left(x+2\right)^2:3=3\)
\(\left(x+2\right)^2=3.3\)
\(\left(x+2\right)^2=9\)
\(\left(x+2\right)^2=3^2\) hoặc \(\left(x+2\right)^2=\left(-3\right)^2\)
\(=>x+2=3\) hoặc \(x+2=-3\)
\(x=3-2\) hoặc \(x=-3-2\)
\(x=1\) hoặc \(x=-5\)
Vậy...
15 + (x + 2)² : 3 = 18
(x + 2)² : 3 = 18 - 15
(x + 2)² : 3 = 3
(x + 2)² = 3 . 3
(x + 2)² = 9
x + 2 = 3 hoặc x + 2 = -3
*) x + 2 = 3
x = 3 - 2
x = 1
*) x + 2 = -3
x = -3 - 2
x = -5
Vậy x = -5; x = 1
a, \(\dfrac{x-2}{15}+\dfrac{x-3}{14}+\dfrac{x-4}{13}+\dfrac{x-5}{12}=4\)
b, \(\dfrac{x+1}{19}+\dfrac{x+2}{18}+\dfrac{x+3}{17}+...+\dfrac{x+18}{2}+18=0\)
Cảm ơn khi đã giúp mình
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
x + 2/3 = 5/6 x có kết quả là: A.2/18 B.1/6 C.2/5 D.15/18
Bài 1 Tìn x : x/16*(2017-1)=2
Bài 2 tìm x : x*15/16-x*4/16=2
Bài 3 Tìm x : 1-(5/4/9+x+7/7/18):15/3/4=0
( Dấu / là dấu gạch phân số Và 5/4/9 ; 15/3/4 ; 7/7/18 Là hỗn số )
bài2 \(x\times\dfrac{15}{16}-x\times\dfrac{4}{16}=2\)
\(x\times\dfrac{11}{16}=2\)
\(x=2:\dfrac{11}{16}\)
\(x=\dfrac{32}{11}\)
Bài 1 :
\(\dfrac{x}{16}\times\left(2017-1\right)=2\)
\(\dfrac{x}{16}\times2016=2\)
\(\dfrac{x}{16}=\dfrac{2}{2016}\)
\(x=\dfrac{2}{2016}\times16\)
\(x=\dfrac{1}{63}\)
1- (5\(\dfrac{4}{9}\) +x+7\(\dfrac{7}{18}\)) : 15\(\dfrac{3}{4}\) = 0
1- (\(\dfrac{49}{9}+x+\dfrac{133}{18}\)) : \(\dfrac{63}{4}=0\)
(\(\dfrac{49}{9}+\dfrac{133}{18}\)+\(x\) ) : \(\dfrac{63}{4}\) = 1 - 0
(\(\dfrac{77}{6}\) + \(x\) ) : \(\dfrac{63}{4}\) = 1
\(\dfrac{77}{6}+x\) = 1 x \(\dfrac{63}{4}\)
\(\dfrac{77}{6}\) + \(x\) = \(\dfrac{63}{4}\)
\(x\) = \(\dfrac{63}{4}\) - \(\dfrac{77}{6}\)
\(x=\) \(\dfrac{35}{12}\)
a) 16 - 18/x| = -8 -14|x|
b) 5 x|+7.(2/x|-3) =4.(x-4)+25
e) 15-3|4x +2| = 3 8) 18 -4.(6-2|x|) = - 3.(4|x|+5)+29
8) 27-5/x -10 = 4|x-10| - 18
h) 510 + 3x|-21 = 7- 2|15+3x|
c) 43x +2|-16= 20
d) 8|x - 1|-4 = 12+6|x-1|
giúp em với
Tìm x 1) X/5=18/15 2)X/12=3/x 3) X - 2 1/2= 3 1/6 4) 2/5× x= 1/2
1: =>x/5=6/5
=>x=6
2: =>x^2=36
=>x=6 hoặc x=-6
3: =>x-5/2=3+1/6=19/6
=>x=19/6+5/2=19/6+15/6=34/6=17/3
4: =>x=1/2:2/5=1/2*5/2=5/4
1. Tìm giá trị của 1 x 5 x 18 + 2 x 10 x 36 + 3 x 15 x 54 / 1 x 3 x 9 + 2 x 6 x 18 + 3 x 9 x 27
Tìm giá trị của 1 x 5 x 18 + 2 x 10 x 36 + 3 x 15 x 54 / 1 x 3 x 9 + 2 x 6 x 18 + 3 x 9 x 27
\(\frac{1.5.18+2.10.36+3.15.54}{1.3.9+2.6.18+3.9.27}=\frac{1.5.18.\left(1+2.2.2+3.3.3\right)}{1.3.9.\left(1+2.2.2+3.3.3\right)}\)
\(=\frac{1.5.18}{1.3.9}=\frac{10}{3}\)
tính nhanh
1. 2/3 + 4/9 + 1/5 + 2/15 +3/2 - 17/18
2. 13/28 x 5/12 - 5/28 x 1/12
3. 19/4 x 15/23 - 15/4 x 7/23 + 15/4 x 11/23
\(1,\frac{2}{3}+\frac{4}{9}+\frac{1}{5}+\frac{2}{15}+\frac{3}{2}-\frac{17}{18}\)
\(< =>\frac{4}{9}+\frac{3}{2}+\left(\frac{2}{3}+\frac{1}{5}+\frac{2}{15}\right)-\frac{17}{18}\)
\(< =>\frac{8}{18}+\frac{27}{18}+\left(\frac{10}{15}+\frac{3}{15}+\frac{2}{15}\right)-\frac{17}{18}\)
\(< =>\frac{35}{18}+1-\frac{17}{18}\)
\(< =>\frac{53}{18}-\frac{17}{18}\)
\(< =>2\)
\(2,\frac{13}{28}\cdot\frac{5}{12}-\frac{5}{28}\cdot\frac{1}{12}\)
\(< =>\left(\frac{13}{28}-\frac{5}{28}\right)\cdot\left(\frac{5}{12}-\frac{1}{12}\right)\)
\(< =>\frac{2}{7}\cdot\frac{1}{3}\)
\(< =>\frac{2}{21}\)
\(3,\frac{19}{4}\cdot\frac{15}{23}-\frac{15}{4}\cdot\frac{7}{23}+\frac{15}{4}\cdot\frac{11}{23}\)
\(< =>\frac{285}{92}-\frac{105}{92}+\frac{165}{92}\)
\(< =>\frac{15}{4}\)
bạn viết dấu gạch ngang của phân số như thế nào đấy nguyen thi hien
Cho P = 5/2 x 1 + 4/1 x 11 + 3/11x2 + 1/2 x 15 + 13/15 x 4 + 15/4 x 43 + 13/43 x 18