-12/15 .x -5=6 1/3
bài 5: tính giá trị biểu thức sau một cách hợp lí
A = -7/21 + ( 1+1/3) B=2/15 +(5/9+ -6/9)
C=9-1/5 + 3/12 ) + -3/4
bài 6
a) x + 7/8 = 13/12 b) - (-6)/12 - x = 9/48
c) x+ 4/6 = 5/25 - (-7)/15 c) x + 4/5 = 6/20 - (-7)/3
`5`
`a, -7/21 +(1+1/3)`
`=-7/21 + ( 3/3 + 1/3)`
`=-7/21+ 4/3`
`=-7/21+ 28/21`
`= 21/21`
`=1`
`b, 2/15 + ( 5/9 + (-6)/9)`
`= 2/15 + (-1/9)`
`= 1/45`
`c, (9-1/5+3/12) +(-3/4)`
`= ( 45/5-1/5 + 3/12)+(-3/4)`
`= ( 44/5 + 3/12)+(-3/4)`
`= 9,05 +(-0,75)`
`=8,3`
`6`
`x+7/8 =13/12`
`=>x= 13/12 -7/8`
`=>x=5/24`
`-------`
`-(-6)/12 -x=9/48`
`=> 6/12 -x=9/48`
`=>x= 6/12-9/48`
`=>x=5/16`
`---------`
`x+4/6 =5/25 -(-7)/15`
`=>x+4/6 =1/5 + 7/15`
`=> x+ 4/6=10/15`
`=>x=10/15 -4/6`
`=>x=0`
`----------`
`x+4/5 = 6/20 -(-7)/3`
`=>x+4/5 = 6/20 +7/3`
`=>x+4/5 = 79/30`
`=>x=79/30 -4/5`
`=>x= 79/30-24/30`
`=>x= 55/30`
`=>x= 11/6`
\(5)\)
\(A=\dfrac{-7}{21}+\left(1+\dfrac{1}{3}\right)\)
\(A=\dfrac{-7}{21}+\dfrac{4}{3}\)
\(A=\dfrac{-7}{21}+\dfrac{28}{21}\)
\(A=1\)
\(--------------\)
\(B=\dfrac{2}{15}+\left(\dfrac{5}{9}+\dfrac{-6}{9}\right)\)
\(B=\dfrac{2}{15}+\dfrac{-1}{9}\)
\(B=\dfrac{18}{135}+\dfrac{-15}{135}\)
\(B=\dfrac{1}{45}\)
\(------------\)
\(C=9-\dfrac{1}{5}+\dfrac{3}{12}+\dfrac{-3}{4}\)
\(C=\dfrac{44}{5}+\dfrac{3}{12}+\dfrac{-3}{4}\)
\(C=\dfrac{528}{60}+\dfrac{15}{60}+\dfrac{-3}{4}\)
\(C=\dfrac{181}{20}+\dfrac{-3}{4}\)
\(C=\dfrac{181}{20}+\dfrac{-15}{20}\)
\(C=\dfrac{83}{10}\)
\(6)\)
\(a)\) \(x+\dfrac{7}{8}=\dfrac{13}{12}\)
\(x=\dfrac{13}{12}-\dfrac{7}{8}\)
\(x=\dfrac{104}{96}-\dfrac{84}{96}\)
\(x=\dfrac{5}{24}\)
\(b)\) \(\dfrac{-6}{12}-x=\dfrac{9}{48}\)
\(\dfrac{-1}{2}-x=\dfrac{3}{16}\)
\(x=\dfrac{-1}{2}-\dfrac{3}{16}\)
\(x=\dfrac{-8}{16}-\dfrac{3}{16}\)
\(x=\dfrac{-11}{16}\)
\(c)\) \(x+\dfrac{4}{6}=\dfrac{5}{25}-\left(-\dfrac{7}{15}\right)\)
\(x+\dfrac{4}{6}=\dfrac{5}{25}+\dfrac{7}{15}\)
\(x+\dfrac{4}{6}=\dfrac{75}{375}+\dfrac{105}{375}\)
\(x+\dfrac{4}{6}=\dfrac{12}{25}\)
\(x=\dfrac{12}{25}-\dfrac{4}{6}\)
\(x=\dfrac{72}{150}-\dfrac{100}{150}\)
\(x=\dfrac{-14}{75}\)
\(d)\) \(x+\dfrac{4}{5}=\dfrac{6}{20}-\left(-\dfrac{7}{3}\right)\)
\(x+\dfrac{4}{5}=\dfrac{6}{20}+\dfrac{7}{3}\)
\(x+\dfrac{4}{5}=\dfrac{18}{60}+\dfrac{140}{60}\)
\(x+\dfrac{4}{5}=\dfrac{79}{30}\)
\(x=\dfrac{79}{30}-\dfrac{4}{5}\)
\(x=\dfrac{79}{30}-\dfrac{24}{30}\)
\(x=\dfrac{11}{6}\)
Giải:
\(A=\dfrac{-7}{21}+\left(1+\dfrac{1}{3}\right)\)
\(A=\dfrac{-7}{21}+\dfrac{4}{3}\)
\(A=\dfrac{-7}{21}+\dfrac{28}{21}\)
\(A=\dfrac{21}{21}=1\)
\(B=\dfrac{2}{15}+\left(\dfrac{5}{9}+\dfrac{-6}{9}\right)\)
\(B=\dfrac{2}{15}+\dfrac{-1}{9}\)
\(B=\dfrac{6}{45}+\dfrac{-5}{45}\)
\(B=\dfrac{1}{45}\)
\(C=\left(9-\dfrac{1}{5}+\dfrac{3}{12}\right)+\dfrac{-3}{4}\)
\(C=\left(\dfrac{44}{5}+\dfrac{1}{4}\right)+\dfrac{-3}{4}\)
\(C=\dfrac{181}{20}+\dfrac{-3}{4}\)
\(C=\dfrac{181}{20}+\dfrac{-15}{20}\)
\(C=\dfrac{166}{20}\)
Bài 6:
\(a)x+\dfrac{7}{8}=\dfrac{13}{12}\)
⇔\(x=\dfrac{13}{12}-\dfrac{7}{8}=\dfrac{5}{24}\)
\(b)\dfrac{-6}{12}-x=\dfrac{9}{48}\)
⇔\(x=\dfrac{-6}{12}-\dfrac{9}{48}=\dfrac{-11}{16}\)
\(c)x+\dfrac{4}{6}=\dfrac{5}{25}-\dfrac{-7}{15}\)
\(\Leftrightarrow x+\dfrac{2}{3}=\dfrac{2}{3}\)
\(\Leftrightarrow x=\dfrac{2}{3}-\dfrac{2}{3}=0\)
\(d)x+\dfrac{4}{5}=\dfrac{6}{20}-\dfrac{-7}{3}\)
⇔\(x+\dfrac{4}{5}=\dfrac{79}{30}\)
⇔\(x=\dfrac{79}{30}-\dfrac{4}{5}=\dfrac{11}{6}\)
5/6 + 5/8 + 3/4
12/15 + 3 + 3/5
4/3 x 7/8 x 5
8/9 x 6/5 : 3
7/12 + 5/8 x 4/3 - 3/4
(8/5 - 7/6) : 13/15 + 1/4
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 số nguyên x, biết:
a) (x-3) + 11 = -25
b) 5 - (x-1) =12 -16
c) (x-14) + (-22) -6 -12
d) (-15) - (15-x) = -6 + (-8)
Tính nhanh :
8/15 + 5/12 - 7/15 - 1/12
9/5 : 7/6 + 3/2 : 7/6 -8/5 x 6/7
0.987 x 3.4 + 0.987 + 5.6 x 0.987
4/5.x = 8/35
2/3.x + 1/4 =7/12
x/10 = 3/10
a,-6/12 < x/12 < -4/12
b, -6/5 + 13/15 < x/15 < -2/5 +1/3
giúp mk nha
cảm ơn mn nhiều
1) \(\frac{4}{5}.x=\frac{8}{35}\Rightarrow x=\frac{8}{25}:\frac{4}{5}\Rightarrow x=\frac{2}{5}\)
\(\frac{2}{3}.x+\frac{1}{4}=\frac{7}{12}\Rightarrow\frac{2}{3}.x=\frac{7}{12}-\frac{1}{4}\)
\(\Rightarrow\frac{2}{3}.x=\frac{1}{3}\)
\(\Rightarrow x=\frac{1}{3}:\frac{2}{3}\)
\(x=\frac{1}{2}\)
\(\frac{x}{10}=\frac{3}{10}\Rightarrow x=\frac{10.3}{10}\Rightarrow x=3\)
a) Ta có: \(\frac{-6}{12}< \frac{x}{12}< \frac{-4}{12}\Rightarrow-6< x< -4\Rightarrow x=-5\)
b) \(\frac{-6}{5}+\frac{13}{15}< \frac{x}{15}< \frac{-2}{5}+\frac{1}{3}\)
\(\Rightarrow\frac{-1}{3}< \frac{x}{15}< \frac{-1}{15}\)
\(\Rightarrow\frac{-5}{15}< \frac{x}{15}< \frac{-1}{15}\)
\(\Rightarrow-5< x< -1\)
\(\Rightarrow x=\left\{-4;-3;-2\right\}\)
Tính nhanh
a,(1+2 +3 +...+99) x (13 x 15 – 12 x 15 –15)
b,2+4+ 6+...+ 98+100–(1+3 +5 +...+97+99)
a)
Ta có : ( 1 + 2 + 3 + ... + 99)
Số số hạng là: ( 99 - 1 ) : 1 + 1 = 100
Tổng là: ( 99 + 1 ) x 100 : 2 = 5000
=> 5000 x ( 13 - 12 - 1 ) x 15
=> 5000 x 10 x 15
=> 50000 x 15
=> 750000
Ko muốn vt nx :))
Thực hiện phép tính: a,(9/10 - 15/16) X (5/12 - 11/15 - 7/20) b,(-1)3 + (-2/3)2: 2 2/3 + 5/6 c,15 X (-1/5)2 + 1/5 - 2 X (-1/2)3 - 1/2 d,22 - (-5/7) + (1/3)4 X 36
a, (\(\dfrac{9}{10}\) - \(\dfrac{15}{16}\)) \(\times\) ( \(\dfrac{5}{12}\) - \(\dfrac{11}{15}\) - \(\dfrac{7}{20}\))
= (\(\dfrac{72}{80}\) - \(\dfrac{75}{80}\)) \(\times\) (\(\)\(\dfrac{25}{60}\) - \(\dfrac{44}{60}\) - \(\dfrac{21}{60}\))
= - \(\dfrac{3}{80}\) \(\times\) (- \(\dfrac{2}{3}\))
= \(\dfrac{1}{40}\)
b, (-1)3 + (- \(\dfrac{2}{3}\))2 : 2\(\dfrac{2}{3}\) + \(\dfrac{5}{6}\)
= -13 + \(\dfrac{4}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{5}{6}\)
= -1 + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{3}{8}\) + \(\dfrac{5}{6}\)
= -1 + \(\dfrac{1}{6}\) + \(\dfrac{5}{6}\)
= -1 + 1
= 0
c, 15 \(\times\) (- \(\dfrac{1}{5}\))2 + \(\dfrac{1}{5}\) - 2 \(\times\) (- \(\dfrac{1}{2}\))3 - \(\dfrac{1}{2}\)
= 15 \(\times\) \(\dfrac{1}{25}\) + \(\dfrac{1}{5}\) - 2 \(\times\) (- \(\dfrac{1}{8}\)) - \(\dfrac{1}{2}\)
= \(\dfrac{3}{5}\) + \(\dfrac{1}{5}\) + \(\dfrac{1}{4}\) - \(\dfrac{1}{2}\)
= \(\dfrac{4}{5}\) - \(\dfrac{1}{4}\)
= \(\dfrac{11}{20}\)
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