tìm x: -3/4+x=-7/12 giúp mik vss
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Bài 1 :
a, \(\frac{3}{4}:x=\frac{5}{12}\)
\(x=\frac{3}{4}:\frac{5}{12}\)
\(x=\frac{9}{5}\)
b, \(x-\frac{1}{2}=\frac{3}{4}:\frac{3}{2}\)
\(x-\frac{1}{2}=\frac{1}{2}\)
\(x=\frac{1}{2}+\frac{1}{2}\)
\(x=1\)
c, \(1\frac{1}{2}x-\frac{1}{2}=\frac{3}{4}\)
\(\frac{3}{2}x-\frac{1}{2}=\frac{3}{4}\)
\(\frac{3}{2}x=\frac{3}{4}+\frac{1}{2}\)
\(\frac{3}{2}x=\frac{5}{4}\)
\(x=\frac{5}{4}:\frac{3}{2}\)
\(x=\frac{5}{6}\)
Bài 2 :
\(A=\frac{-3}{5}+\left(\frac{-2}{5}-99\right)\)
\(A=\frac{-3}{5}+\frac{-2}{5}-99\)
\(A=\left(-1\right)-99\)
\(A=-100\)
\(B=\left(7\frac{2}{3}+2\frac{3}{5}\right)-6\frac{2}{3}\)
\(B=\left(\frac{23}{3}+\frac{13}{5}\right)-\frac{20}{3}\)
\(B=\frac{23}{3}+\frac{13}{5}-\frac{20}{3}\)
\(B=\left(\frac{23}{3}-\frac{20}{3}\right)+\frac{13}{5}\)
\(B=1+\frac{13}{5}\)
\(B=\frac{18}{5}\)
\(p\left(x\right)=x^2+0.x-9\)
\(P\left(x\right)=x^2-9\)
Để \(P\left(x\right)c\text{ó}gtnn\Rightarrow x^2=0\)
Min P(x)=-9\(\Leftrightarrow x=0\)
a) (-2) . ( x+7 ) + (-5) = 7
<=>(-2).(x+7)=7+5
<=>x+7=12:(-2)
<=>x+7=-6
<=>x=(-6)-7
<=>x=-13
Vậy x=-13
b)(x+4) : (-7) = 14
<=>x+4=14 x (-7)
<=>x+4=-98
<=>x=-98-4
<=>x=-102
Vậy x= -102
c) 72 : ( x+5) - 4 = -12
<=>72:(x+5)=(-12)+4
<=>x+5=72:(-8)
<=>x+5=-9
<=>x=-9-5
<=>x=-14
Vậy x= -14
d) (x+3) : (-6 ) + 12 = 8
<=>(x+3) :(-6)=8-12
<=>x+3=(-4)x(-6)
<=>x+3=24
<=>x=24-3
<=>x=21
Vậy x= 21
bạn đã kiểm tra kĩ chưa vậy?mình đọc đề câu B mà loạn não luôn á;-;
a) 3/8 . x = 9/8 - 1
3/8 . x = 1/8
x = 1/8 : 3/8
x = 1/3
b) 4/5 . x = 7/5 - 1/5
4/5 . x = 6/5
x = 6/5 : 4/5
x = 3/2
c) 12/7 : x + 2/3 = 7/5
12/7 : x = 7/5 - 2/3
12/7 : x = 11/15
x = 12/7 : 11/15
x = 180/77
d) 3.(x + 7) - 15 = 27
3.(x + 7) = 27 + 15
3.(x + 7) = 42
x + 7 = 42 : 3
x + 7 = 14
x = 14 - 7
x = 7
a) \(\dfrac{3}{8}x=\dfrac{9}{8}-1\)
\(\Rightarrow\dfrac{3}{8}x=\dfrac{1}{8}\)
\(\Rightarrow x=\dfrac{1}{8}:\dfrac{3}{8}=\dfrac{1}{3}\)
b) \(\dfrac{4}{5}x=\dfrac{7}{5}-\dfrac{1}{5}\)
\(\Rightarrow\dfrac{4}{5}x=\dfrac{6}{5}\)
\(\Rightarrow x=\dfrac{6}{5}:\dfrac{4}{5}=\dfrac{3}{2}\)
c) \(\dfrac{12}{7}:x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\Rightarrow\dfrac{12}{7}:x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\Rightarrow\dfrac{12}{7}:x=\dfrac{11}{15}\)
\(\Rightarrow x=\dfrac{12}{7}:\dfrac{11}{15}=\dfrac{180}{77}\)
d) \(3\left(x+7\right)-15=27\)
\(\Leftrightarrow3\left(x+7\right)=42\)
\(\Leftrightarrow x+7=14\Leftrightarrow x=7\)
`a, x/7 =-4/14`
`=> 14x=7.(-4)`
`=>14x=-28`
`=>x=-28:14`
`=>x=-2`
`b,x/2=-2/-x`
`=>x/2=2/x`
`=>x.x=2.2`
`=>x^2=4`
`=>x= +-2`
`c,(x-1)/5=5/(x-1)`
`=>(x-1)^2 = 5.5`
`=>(x-1)^2=25`
`=>(x-1)^2=5^2`
\(\Rightarrow\left[{}\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\)
`d,x+3/2=-12/16`
`=>x=-12/16 -3/2`
`=>x= -12/16 - 24/16`
`=>x= -36/16`
`=>x=-9/4`
\(\left(x-\dfrac{4}{7}\right):-\dfrac{1}{3}=1\)
\(\Rightarrow x-\dfrac{4}{7}=1\cdot-\dfrac{1}{3}\)
\(\Rightarrow x-\dfrac{4}{7}=-\dfrac{1}{3}\)
\(\Rightarrow x=-\dfrac{1}{3}+\dfrac{4}{7}\)
\(\Rightarrow x=\dfrac{5}{12}\)
___________________
\(\dfrac{2}{3}-\dfrac{7}{4}:x=\dfrac{5}{6}\)
\(\Rightarrow\dfrac{7}{4}:x=\dfrac{2}{3}-\dfrac{5}{6}\)
\(\Rightarrow\dfrac{7}{4}:x=-\dfrac{1}{6}\)
\(\Rightarrow x=\dfrac{7}{4}:-\dfrac{1}{6}\)
\(\Rightarrow x=-\dfrac{21}{2}\)
(x - 4/7) : (-1/3) = 1
x - 4/7 = -1/3
x = -1/3 +4/7
x = 5/21
--------------------
2/3 + 7/4 : x = 5/6
7/4 : x = 5/6 - 2/3
7/4 : x = 1/6
x = 7/4 : 1/6
x = 21/2
\(-\dfrac{3}{4}+x=-\dfrac{7}{12}\\ x=-\dfrac{7}{12}-\left(-\dfrac{3}{4}\right)\\ x=-\dfrac{7}{12}+\dfrac{3}{4}\\ x=\dfrac{-7+3.3}{12}\\ x=\dfrac{-7+9}{12}\\ x=\dfrac{2}{12}=\dfrac{1}{6}\)
\(\dfrac{-3}{4}+x=-\dfrac{7}{12}\)
\(x=\dfrac{-7}{12}-\dfrac{-3}{4}\)
\(x=\dfrac{-7}{12}+\dfrac{9}{12}\)
\(x=\dfrac{2}{12}=\dfrac{1}{6}\)