TÌM X:
(x+1) :(3/1*2+3/2*3+3/3*4+.........+3/14*15)=1và 1/14
Tìm x
a) -x/27 -1 = 2/3
b) x - 4 = -14/35 : 20/-21
c) x + 2/3 = -1/12 . -4/5
d) 1/5 - 3/5x = -15/14 :20/-21
e) -3/7x = 3/5 . 28/9
f)1/2x + 3/5x = -2/3
a: =>x/27+1=-2/3
=>x/27=-5/3
=>x=-45
b: \(\Leftrightarrow x-4=\dfrac{2}{5}:\dfrac{20}{21}=\dfrac{2}{5}\cdot\dfrac{21}{20}=\dfrac{42}{100}=\dfrac{21}{50}\)
=>x=221/50
c: \(\Leftrightarrow x+\dfrac{2}{3}=\dfrac{4}{60}=\dfrac{1}{15}\)
=>x=1/15-2/3=1/15-10/15=-9/15=-3/5
d: \(\Leftrightarrow x\cdot\dfrac{3}{5}=\dfrac{1}{5}-\dfrac{15}{14}\cdot\dfrac{21}{20}\)
=>\(x\cdot\dfrac{3}{5}=\dfrac{1}{5}-\dfrac{3}{2}\cdot\dfrac{3}{4}=\dfrac{1}{5}-\dfrac{9}{8}=\dfrac{-37}{40}\)
=>x=-37/24
e: =>-3/7x=84/45
=>x=-196/45
f: =>11/10x=-2/3
=>x=-20/33
Bài 4: So sánh
1)2√3+√27và √74
2)3+√5và2√2+√6
3)√27+√26+1và√48
4) √15- √14 và √14- √13
\(1,2\sqrt{3}+\sqrt{27}=2\sqrt{3}+3\sqrt{3}=5\sqrt{3}=\sqrt{75}>\sqrt{74}\\ 2,\left(3+\sqrt{5}\right)^2=14+6\sqrt{5}\\ \left(2\sqrt{2}+\sqrt{6}\right)^2=14+4\sqrt{3}\\ 6\sqrt{5}=\sqrt{180}>\sqrt{48}=4\sqrt{3}\\ \Rightarrow3+\sqrt{5}>2\sqrt{2}+\sqrt{6}\\ 3,3\sqrt{3}+\sqrt{26}+1>3\sqrt{3}+\sqrt{3}\left(\sqrt{26}>\sqrt{3}\right)\\ \Rightarrow\sqrt{27}+\sqrt{26}+1>4\sqrt{3}=\sqrt{48}\\ 4,\dfrac{1}{\sqrt{15}+\sqrt{14}}< \dfrac{1}{\sqrt{14}+\sqrt{13}}\left(\sqrt{15}+\sqrt{14}>\sqrt{14}+\sqrt{13}\right)\\ \Rightarrow\sqrt{15}-\sqrt{14}< \sqrt{14}-\sqrt{13}\)
Bài6:Tìm x
a,x+1/4-3/8=7/12
b,x-3/14=5/14+15/21
c,3/10:x=1/10-1/20
d,x:8/25=1/2×4/5
tính trừ bt nha bạn vế thương thì cũng tĩnh ra xong mới tính nha
a, \(x\) + \(\dfrac{1}{4}\) - \(\dfrac{3}{8}\) = \(\dfrac{7}{12}\)
\(x\) - \(\dfrac{1}{8}\) = \(\dfrac{7}{12}\)
\(x\) = \(\dfrac{7}{12}\) + \(\dfrac{1}{8}\)
\(x\) = \(\dfrac{17}{24}\)
b, \(x\) - \(\dfrac{3}{14}\) = \(\dfrac{5}{14}\) + \(\dfrac{15}{21}\)
\(x\) - \(\dfrac{3}{14}\) = \(\dfrac{15}{14}\)
\(x\) = \(\dfrac{15}{14}\) + \(\dfrac{3}{14}\)
\(x\) = \(\dfrac{9}{7}\)
a)x+3/5=-1/15
b) x/14=1/7-3/14
C)-1/2x+1/5=3/10
d) 4/5-(2/15+x)=1/15
a) x + 3/5 = -1/15
=> x = -1/15 - 3/5
=> x = -2/3
b) x/14 = 1/7 - 3/14
=> x/14 = -1/14
=> x = -1
c) -1/2x + 1/5 = 3/10
=> -1/2x = 3/10 - 1/5
=> -1/2x = 1/5
=> x = 1/5 : (-1/2)
=> x = -2/5
d) 4/5 - (2/15 + x) = 1/15
=> 4/5 - 2/15 - x = 1/15
=> 2/3 - x = 1/15
=> x = 2/3 - 1/15
=> x = 3/5
BÀI 1: Tính
1) -(-10)-(+14)
2) -(+15)-12
3) (-11)-(-13)
4) -(-13)-(-10)
5) -4-(+7)
BÀI 2: Tìm x biết:
1) x+(-5)= -(-7)
2) x-8= -(+10)
3) x-(-12)= 14
4) x-(+3)= -17
5) x+20= -(-23)
BÀI 3: Tính:
1) 17-(-19)-(+25)
2) -[-13]-[15]+(-20)
3) [-17]-(-16)-(+23)
4) -(-25)-[-14]+[-17]
BÀI 1: Tính
1) -(-10)-(+14)=10-14=-4
2) -(+15)-12=-15-12=-27
3) (-11)-(-13)=-11+13=2
4) -(-13)-(-10)=13+10=23
5) -4-(+7)=-4-7=-11
Bài 2 : tìm x:
a)x+(-5)=-(-7)
x=7+(-5)
x=2
vậy x=2
b)x-8=-(+10)
x-8=10
x=10+8
x=18
vậy x=18
c)x-(-12)=14
x+12=14
x=14-12
x=2
vậy x=2
d)x-(+3)=-17
x-3=17
x=17+3
x=20
vậy x=20
e)x+20=-(-23)
x+20=23
x=23-20
x=3
vậy x=3
BÀI 3:tính
a)17-(-9)-(+25)
=17+9-25
=26-25
=1
b)-[-13]-15+(-20)
=13-15-20
=-2-20
=-22
c)-17-(-16)-23
=-17+16-23
=-1-23
=-24
d)-(-25)-(-14)+(-17)
=25+14-17
=39-17
=22
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haha ối giời ơi
Bài 1: Tìm x
a, x + 15/16 + 7/8 = 15/4 b, x - 27/28 - 9/14 = 13/7
c, x nhân 1/5 + x + 1/6 = 2/3 d, x: 14 = 1/4 + 2/9 + 3/4
a)\(x+\frac{15}{16}+\frac{7}{8}=\frac{15}{4}\)
\(x+\frac{29}{16}=\frac{15}{4}\)
\(x=\frac{15}{4}-\frac{29}{16}\)
\(x=\frac{31}{16}\)
b)\(x-\frac{27}{28}-\frac{9}{14}=\frac{13}{7}\)
\(x-\frac{45}{28}=\frac{13}{7}\)
\(x=\frac{13}{7}+\frac{45}{28}\)
\(x=\frac{97}{28}\)
c)\(x\times\frac{1}{5}+x+\frac{1}{6}=\frac{2}{3}\)
\(x\times\frac{1}{5}+x=\frac{2}{3}-\frac{1}{6}\)
\(x\times\left(\frac{1}{5}+1\right)=\frac{1}{2}\)
\(x\times\frac{6}{5}=\frac{1}{2}\)
\(x=\frac{1}{2}:\frac{6}{5}\)
\(x=\frac{5}{12}\)
d)\(x:14=\frac{1}{4}+\frac{2}{9}+\frac{3}{4}\)
\(x:14=\frac{11}{9}\)
\(x=\frac{11}{9}\times14\)
\(x=\frac{154}{9}\)
#H
bài 1:Tìm x biết
a,X x 3/4 = 9/14 b,x : 5/9 = 3/10
bài 2:Tính
a, 3/10 + 2/5 : 4/15 b, 4/7 x 3 + 2/3 x 2
Giúp mình với nhé
Bài 1:
a) \(x.\dfrac{3}{4}=\dfrac{9}{14}\)
\(\Rightarrow x=\dfrac{9}{14}:\dfrac{3}{4}\)
\(\Rightarrow x=\dfrac{6}{7}\)
b) \(x:\dfrac{5}{9}=\dfrac{3}{10}\)
\(\Rightarrow x=\dfrac{3}{10}.\dfrac{5}{9}\)
\(\Rightarrow x=\dfrac{1}{6}\)
Bài 2:
a) \(\dfrac{3}{10}+\dfrac{2}{5}:\dfrac{4}{15}=\dfrac{3}{10}+\dfrac{3}{2}=\dfrac{9}{5}\)
b) \(\dfrac{4}{7}.3+\dfrac{2}{3}.2=\dfrac{12}{7}+\dfrac{4}{3}=\dfrac{64}{21}\)
giaỉ phương trình
a) (x-2)/7+(x-1)/8 = (x-4)/5 + (x-3)/6
b) (x+1)/15 + (x+2)/14 = (x+3)/15+ (x+4)/14
Mình làm mẫu câu a nha
a, pt <=> ( x-2/7 - 1 ) + ( x-1/8 - 1 ) = ( x-4/5 - 1 ) + ( x-3/6 - 1 )
<=> x-9/7 + x-9/8 = x-9/5 + x-9/6
<=> x-9/5 + x-9/6 - x-9/7 - x-9/8 = 0
<=> (x-9).(1/5+1/6-1/9-1/8) = 0
<=> x-9 = 0 ( vì 1/5+1/6-1/9-1/8 > 0 )
<=> x = 9
Vậy x = 9
Tk mk nha
Bài 3. Tìm x biết:
1) |x| = 10 2) |x - 8| = 0 3) 7 + |x| = 12
4) |x + 1| = 3 5) 15 - x = 16 - (14 - 42) 6) 210 - (x - 12) = 168
1/ `|x|=10<=> x=\pm 10`
2/ `|x-8|=0<=>x-8=0<=>x=8`
3/ `7+|x|=12<=>|x|=5<=>x=\pm 5`
4/ `|x+1|=3`
$\Leftrightarrow\left[\begin{array}{1}x+1=3\\x+1=-3\end{array}\right.\\\Leftrightarrow\left[\begin{array}{1}x=3\\x=-4\end{array}\right.$
5/ `15-x=16-(14-42)`
`<=>15-x=16+28`
`<=>15-x=44`
`<=>x=-29`
6/ `210-(x-12)=168`
`<=>210-x+12=168`
`<=>222-x=168`
`<=>x=54`
1.
\(\left|x\right|=10\Leftrightarrow x=\pm10\)
2.
\(\left|x-8\right|=0\Leftrightarrow x-8=0\Leftrightarrow x=8\)
3.
\(7+\left|x\right|=12\Leftrightarrow\left|x\right|=5\Leftrightarrow x=\pm5\)