6 . 2x + 3 . 2x= 72
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a, \(\Leftrightarrow2x^2=72\)
\(\Leftrightarrow x^2=36\)
\(\Leftrightarrow x=\pm6\)
Vậy ...
\(b,\Leftrightarrow\dfrac{3}{5}x-0,75=2\dfrac{4}{5}.\dfrac{3}{7}=\dfrac{6}{5}\)
\(\Leftrightarrow\dfrac{3}{5}x=\dfrac{6}{5}+0,75=\dfrac{39}{20}\)
\(\Leftrightarrow x=\dfrac{39}{20}:\dfrac{3}{5}=\dfrac{13}{4}\)
Vậy ...
\(c,\Leftrightarrow2x=1\dfrac{5}{6}.\dfrac{6}{11}-\dfrac{3}{10}=\dfrac{7}{10}\)
\(\Leftrightarrow x=\dfrac{7}{10}:2=\dfrac{7}{20}\)
Vậy ...
\(d,\Leftrightarrow\dfrac{1}{x-7\dfrac{1}{3}}=1.5:2\dfrac{1}{4}=\dfrac{2}{3}\)
\(\Leftrightarrow x-7\dfrac{1}{3}=\dfrac{3}{2}\)
\(\Leftrightarrow x=\dfrac{3}{2}+7\dfrac{1}{3}=\dfrac{53}{6}\)
Vậy ...
a) 2x2 - 72 = 0
\(\Rightarrow\) 2x2 = 72
\(\Rightarrow\) x2 = 36 = 62 = (- 6)2
\(\Rightarrow\) x = 6 hoặc x = - 6
Vậy x = 6 hoặc x = - 6
b) (\(\dfrac{3}{5}\)x - 0,75) : \(\dfrac{3}{7}\) = \(2\dfrac{4}{5}\)
\(\Rightarrow\) (\(\dfrac{3}{5}\)x - 0,75) : \(\dfrac{3}{7}\) = \(\dfrac{14}{5}\)
\(\Rightarrow\) \(\dfrac{3}{5}\)x - \(\dfrac{3}{4}\) = \(\dfrac{6}{5}\)
\(\Rightarrow\) \(\dfrac{3}{5}\)x = \(\dfrac{39}{20}\)
\(\Rightarrow\) x = \(\dfrac{13}{4}\)
Vậy x = \(\dfrac{13}{4}\)

a.2x - 138 =72
\(\Leftrightarrow\)2x = 210 \(\Leftrightarrow\)x= 105
b.32 - 3x =66 : 65
\(\Leftrightarrow\)9 - 3x =6 \(\Leftrightarrow\)3x =3 \(\Leftrightarrow\)x=1
c.( 64 -4x).3 =24
\(\Leftrightarrow\)64-4x =8 \(\Leftrightarrow\)4x = 56 \(\Leftrightarrow\)x=14
d.3x.6 - 39 =123
\(\Leftrightarrow\) 3x . 6 = 162 \(\Leftrightarrow\)3x =27 \(\Leftrightarrow\)x =3

Bài giải
a, \(-2\left(2x-8\right)+3\left(4-2x\right)=-72-5\left(3x-7\right)\)
\(-4x+8+12-6x=-72-15x+7\)
\(-10x+20=-65-15x\)
\(-10x+15x=-65-20\)
\(5x=-85\)
\(x=-85\text{ : }5\)
\(x=-17\)
b, \(3\left|2x^2-7\right|=33\)
\(\left|2x^2-7\right|=33\text{ : }3\)
\(\left|2x^2-7\right|=11\)
\(\Rightarrow\orbr{\begin{cases}2x^2-7=-11\\2x^2-7=11\end{cases}}\Rightarrow\orbr{\begin{cases}2x^2=-4\text{ ( loại ) }\\2x^2=18\end{cases}}\Rightarrow\text{ }x^2=9\text{ }\Rightarrow\text{ }x=\pm3\)
\(\Rightarrow\text{ }x=\pm3\)

\(6^{2x-2}.2=72\)
\(6^{2x-2}=72:2\)
\(6^{2x-2}=36\)
\(6^{2x-2}=6^2\)
\(\Leftrightarrow2x-2=2\)
\(\Leftrightarrow2x=2+2\)
\(\Leftrightarrow2x=4\)
\(\Leftrightarrow x=4:2\)
\(\Leftrightarrow x=2\)
Vậy \(x=2\)

`- 9 . ( x - 6 ) + 20 = 56`
`=> -9 . ( x - 6 ) = 56-20`
`=> -9 . ( x - 6 ) =36`
`=>x-6=36:(-9)`
`=>x-6=-4`
`=>x=-4+6`
`=>x=2`
`-------------`
` ( 245 - x ) + 7^2=149`
`=>( 245 - x ) +49=149`
`=> 245 - x =149-49`
`=> 245 - x =100`
`=>x=245-100`
`=>x=145`
`------------`
`(2^x-3).7=35`
`=> 2^x-3=35:7`
`=> 2^x-3=5`
`=>2^x=5+3`
`=>2^x=8`
`=>2^x=2^3`
`=>x=3`

-2(2x-8)+3(4-2x)=-72-5(3x-7)
-2.2x-(-2).8+3.4-3.2x=-72-5.3x+5.7
-4x+16+12-6x=-72-15x+35
-4x-6x+15x=-72+35-16-12
5x=-65
x=-65:5
x=-13

\(-2\left(2x-8\right)+3\left(4-2x\right)=-72-5\left(3x-7\right)\)
\(\Leftrightarrow-4x-16+12-6x=-72-15x+35\)
\(\Leftrightarrow-10x-4=-37-15x\)
\(\Leftrightarrow-10x+15x=-37+4\)
\(\Leftrightarrow5x=-33\)
\(\Leftrightarrow x=\frac{-33}{5}\)
6 . 2x + 3 . 2x= 72
( 6 + 3 ) . 2x = 72
9 . 2x = 72
2x = 72 : 9
2x = 8
2x = 23
=> x = 3
6 . 2x + 3 . 2x= 72
2x . (6+3) = 72
2x . 9 = 72
2x = 8
2x = 23
x = 3