Tìm x:
2(x+5) = (x+31)x(-1)
bài 1 : tìm x
a, 1/5=5=1/2 b, 11/5+x=9
c,5-x=7/17 d, x-1/3=16/5:3/2
e,8/9:x=11/2 g, x:31/5=2+7/2
h,7/8x íc=29/2-2
giải hết ra cho mink nha
1, Tính :
a, 5-(-3)mu2-14(-8)+(-31)
b, 6(-2 ) mu3 +5(-4)-(-12)
c, -31-[82-(-17)
2, Tìm các số nguyên x,y biết (x-1)(x+y)=3
3,Tìm x thuộc Z biết :
a, 12-|x+7|=12
b, 48:|-x+3|=12
c,|x-5|=5-x
\(12-\left|x+7\right|=12\)
\(\Rightarrow\left|x+7\right|=12-12\)
\(\Rightarrow\left|x+7\right|=0\)
\(\Rightarrow x+7=0\)
\(\Rightarrow x=0-7\)
\(\Rightarrow x=-7\)
tìm x biết
x/7-3/7+1/2=31/140
5/12+5/x-1/8=1/2
Bài làm
a) \(\frac{x}{7}-\frac{3}{7}+\frac{1}{2}=\frac{31}{140}\)
\(\frac{x}{7}=\frac{31}{140}-\frac{1}{2}+\frac{3}{7}\)
\(\frac{x}{7}=\frac{31}{140}-\frac{70}{140}+\frac{60}{140}\)
\(\frac{x}{7}=\frac{21}{140}\)
\(\frac{x}{7}=\frac{3}{20}\)
=> \(x.20=3.7\)
=> \(x=\frac{3.7}{20}\)
=> \(x=\frac{21}{20}\)
Vậy \(x=\frac{21}{20}\)
b) \(\frac{5}{12}+\frac{5}{x}-\frac{1}{8}=\frac{1}{2}\)
\(\frac{5}{x}=\frac{1}{2}+\frac{1}{8}-\frac{5}{12}\)
\(\frac{5}{x}=\frac{12}{24}+\frac{3}{24}-\frac{10}{24}\)
\(\frac{5}{x}=\frac{5}{24}\)
=> \(5.24=5.x\)
=> \(x=\frac{5.24}{5}\)
=> \(x=24\)
Vậy \(x=24\)
# Học tốt #
1/4 x 2/6 x3/8 x 4/10 x 5/12 x....x 30/62 x 31/64=2n. Tìm n
<=> \(\frac{1.2.3....31}{4.6.8....64}=2^n\Rightarrow\frac{1.2.3....30.31}{2\left(2.3.4.5...31\right).32}=2^n\Leftrightarrow\frac{1}{2.32}=2^n\Leftrightarrow\frac{1}{2^6}=2^n\)
=> 2^6.2^n = 1
=> 2^ (n + 6 ) = 2^0
=> n+ 6 = 0
=> n = - 6
\(\frac{1}{4}.\frac{2}{6}.\frac{3}{8}....\frac{31}{64}=\frac{1.2.3....31}{4.6.8....64}=\frac{1.2.3....31}{2.3.2.4....2.32}=\frac{1.2.3....31}{2^{30}.\left(3.4....32\right)}=\frac{2}{2^{30}.32}=\frac{1}{2^{34}}=2^{-34}=2^n=>n=-34\)
2^n × 2³¹ = \(\dfrac{ }{ }\)2/4×4/6×6/8×...×62/64
2^n×2³¹=1/32=2^-5
2^n=2^-5 ÷ 2³¹=2^-36
=>n=-36
Bài 1: Tìm x biết \(\frac{5^{x+2}+5^{x+1}+5^x}{31}=\frac{9^{2x}+9^{2x+1}+9^{2\left(x+1\right)}}{91}\)
a) Tìm tập hợp các số nguyên x, biết rằng\(4\dfrac{5}{9}:2\dfrac{5}{18}-7< x< \left(3\dfrac{1}{5}:3,2+4,5.1\dfrac{31}{45}\right):\left(-21\dfrac{1}{2}\right)\)
b) tìm x, biết \(\left|x+\dfrac{1}{2}\right|+\left|x+\dfrac{1}{6}\right|+\left|x+\dfrac{1}{12}\right|+\left|x+\dfrac{1}{20}\right|+....+\left|x+\dfrac{1}{110}\right|-11x\)
c)Tính gt biểu thức \(C=2x^3-5y^3+2015\) tại x,y thỏa mãn \(\left|x-1\right|+\left(y+2\right)^{20}=0\)
Tìm x, biết :
1, [ 50+ (55 - x) ] .17= 1700
2, 720:[ 31- (2.x-5) ]= 72
[50+(55-x)].17=1700
[50+(55-x)]=1700:17
[50+(55-x)]=100
(55-x)=100-50
(55-x)=50
x=50+55
x=105
720:[31-(2.x-5)]=72
[31-(2.x-5)]=720:72
[31-(2.x-5)]=10
(2.x-5)=31-10
(2.x-5)=21
2.x=21+5
2.x=26
x=26:2
x=13
\(\left[50+\left(55-x\right)\right].17=1700\)
\(50+55-x=1700:17\)
\(105-x=100\)
\(x=105-100\)
\(x=5\)
vay \(x=5\)
2) \(720:\left[31-\left(2x-5\right)\right]=72\)
\(31-2x+5=720:72\)
\(36-2x=10\)
\(2x=36-10\)
\(2x=26\)
\(x=13\)
vay \(x=13\)
[50+(55-x)] .17 =1700
50+(55 - x) =1700 :17
50+(55 - x) =100
55 - x =100 - 50
55-x = 50
x = 55- 50
x =5
Tìm x thuộc Z : ( chi tiết) mình cần gấp
a) 3/2 + -1/3 < x/6 <1/9 +31/18
b)-5/12 + 7/12 + -1/12 < x/12 < 2/15 + 1/5
\(a.\dfrac{3}{2}+\dfrac{-1}{3}< \dfrac{x}{6}< \dfrac{1}{9}+\dfrac{31}{18}\)
\(\Leftrightarrow\dfrac{7}{6}< \dfrac{x}{6}< \dfrac{11}{6}\)
\(\Leftrightarrow7< x< 11\)
\(\Leftrightarrow x\in\left\{8;9;10\right\}\)
\(b.\dfrac{-5}{12}+\dfrac{7}{12}+\dfrac{-1}{12}< \dfrac{x}{12}< \dfrac{2}{15}+\dfrac{1}{5}\)
\(\Leftrightarrow\dfrac{1}{12}< \dfrac{x}{12}< \dfrac{1}{3}\)
\(\Leftrightarrow\dfrac{1}{12}< \dfrac{x}{12}< \dfrac{4}{12}\)
\(\Leftrightarrow1< x< 4\)
\(\Leftrightarrow x\in\left\{2;3\right\}\)
Tìm X : a) (1/15 + 1/35 + 1/63) x X =1
b) X - (31/5 + 31/15 + 31/35 + 31/63 + 31/99 + 31/143) =9/13
Các bạn giải thật chi tiết cho mình nhé!!