`a)(x-2)(x^2+2x+4)-x(x-3)(x+3)=26`

`<=>x^3-2^3-x(x^2-9)=26`

`<=>x^3-8-x^3+9x=26`

`<=>9x-8=26`

`<=>9x=34`

`<=>x=34/9`

`b)(x-3)(x^2+3x+9)-x(x+4)(x-4)=21`

`<=>x^3-3^3-x(x^2-16)=21`

`<=>x^3-27-x^3+16x=21`

`<=>16x-27=21`

`<=>16x=48`

`<=>x=3`

\(a,\Rightarrow 2x^2-10x-3x-2x^2=26\\ \Rightarrow -13x=26\\ \Rightarrow x=-2\\ b, \Rightarrow -2x^2+3x+3-3x-3+2x^2-x=18\\ \Rightarrow -x=18\Rightarrow x=-18\)

\(a,\Rightarrow2x^2-18x-2x^2=0\\ \Rightarrow-18x=0\Rightarrow x=0\\ b,\Rightarrow2x^2-5x-12+x^2-7x+10=3x^2-17x+20\\ \Rightarrow5x=22\Rightarrow x=\dfrac{22}{5}\)

b . 49x^2 - 81 = 0 

=> 49x^2 = 81 

rồi giải ra nhé 

a ) 2x ( x - 5 ) - x ( 3 + 2x ) = 26

2x² - 10x - 3x - 2x² = 26

- 13x = 26

x = 26 : ( -13 )

x = -2

b) 49x² - 81 = 0

( 7x - 9 )( 7x + 9 ) = 0

Th1 :

7x - 9 = 0

7x = 9

x = \(\frac{9}{7}\)

Th2

7x + 9 = 0

7x = -9

x = \(-\frac{9}{7}\)

Vay x = \(\frac{9}{7}\) hoac x = \(-\frac{9}{7}\)

bn này k bao gio tra cong ng khac, ngu j ma lam

a) 2³.(20 - 2x) = 4.2⁵

8.(20 - 2x) = 4.32

8.(20 - 2x) = 128

20 - 2x = 128 : 8

20 - 2x = 16

2x = 20 - 16

2x = 4

x = 4 : 2

x = 2

b) 3²⁺ˣ = 81

3²⁺ˣ = 3⁴

2 + x = 4

x = 4 - 2

x = 2

1)

`7x^2 -49x=0`

`<=>x(7x-49)=0`

\(< =>\left[{}\begin{matrix}x=0\\7x-49=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=0\\x=7\end{matrix}\right.\)

2)

`8x^2 -16x=0`

`<=>x(8x-16)=0`

\(< =>\left[{}\begin{matrix}x=0\\8x-16=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=0\\x=2\end{matrix}\right.\)

3)

`2x^3 +40x=0`

`<=>x(2x^2 +40)=0`

`<=>x=0` hoặc`2x^2 +40=0`

`<=>x=0` hoặc `2x^2 =-40` (vô lí vì `2x^2` luôn lớn hơn hoặc bằng 0)

`<=>x=0`

4)

`-x^3 +16x=0`

`<=>x^3 -16x=0`

`<=>x(x^2 -16)=0`

\(< =>\left[{}\begin{matrix}x=0\\x^2-16=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=0\\x^2=16\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=0\\x=4\\x=-4\end{matrix}\right.\)

2x.(x - 5) - x.(3 + 2x) = 26

=> (2x² - 10x) - (3x + 2x²) = 26

=> 2x² - 10x - 3x - 2x² = 26

=> -13x = 26

=> x = 26 : (-13)

=> x = -2

2x.﴾x ‐ 5﴿ ‐ x.﴾3 + 2x﴿ = 26 => ﴾2x 2 ‐ 10x﴿ ‐ ﴾3x + 2x 2 ﴿ = 26 => 2x 2 ‐ 10x ‐ 3x ‐ 2x 2 = 26 => ‐13x = 26 => x = 26 : ﴾‐13﴿ => x = ‐2

3^x-5 . 3^2x = 81

3^(x-5)+2x = 3⁴

\(\Rightarrow\)( x - 5 ) + 2x = 4

\(\Rightarrow\)3x - 5 = 4

\(\Rightarrow\)3x = 4 + 5

\(\Rightarrow\)3x = 9

\(\Rightarrow\)x = 9 : 3

\(\Rightarrow\)x = 3

a) 3x(4x-3)-2x(5-6x)=0

\(\Leftrightarrow12x^2-9x-10x+12x^2=0\)

\(\Leftrightarrow24x^2-19x=0\)

\(\Leftrightarrow x\left(24x-19\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\24x-19=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\24x=19\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{19}{24}\end{matrix}\right.\)

Vậy x=0 hoặc x=\(\dfrac{19}{24}\)

b) 5(2x-3)+4x(x-2)+2x(3-2x)=0

\(\Leftrightarrow\)10x-15+4x²-8x+6x-4x²=0

\(\Leftrightarrow8x-15=0\)

\(\Leftrightarrow8x=15\)

\(\Leftrightarrow x=\dfrac{15}{8}\)

vậy x=\(\dfrac{15}{8}\)

c)3x(2-x)+2x(x-1)=5x(x+3)

\(\Leftrightarrow6x-3x^2+2x^2-2x=5x^2+15x\\ \Leftrightarrow4x-x^2=5x^2+15x\\ \Leftrightarrow4x-x^2-5x^2-15x=0\\ \)

\(\Leftrightarrow-6x^2-11x=0\\ \Leftrightarrow-x\left(6x+11\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}-x=0\\6x+11=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\6x=-11\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{-11}{6}\end{matrix}\right.\)

Vậy x=0 hoặc x=\(\dfrac{-11}{6}\)