l8 học đặt r đk 

đặt  t=x+5

=>pt: 

\(\left(t-3\right)^4+\left(t+3\right)^4=272\\ \Leftrightarrow t^4-4t^3+54t^2-108t+81+t^4+4t^3+54t^2+108t+81=271\\ \Leftrightarrow2t^4+108t^2-110=0\\ \Leftrightarrow\left(t^2-1\right)\left(2t^2+110\right)=0\\ \Leftrightarrow t^2=1\)

( 2t^2 +110 > 0 mọi x)

\(\Leftrightarrow\left[{}\begin{matrix}t=1\Rightarrow x=-4\\t=-1\Rightarrow x=-6\end{matrix}\right.\)

(12x-4³).8³=4.8⁴

=> 12x-4³=4.8⁴:8³

=> 12x-64=4.8

=> 12x-64=32

=> 12x=32+64

=> 12x=96

=> x=96:12

=> x=8

(3x-2⁴).7³=2.7⁴

=> 3x-2⁴=2.7⁴:7³

=> 3x-16=2.7

=> 3x-16=14

=> 3x=14+16

=> 3x=30

=> x=10

2^x+2^x+4=272

=> 2^x.(1+2⁴)=272

=> 2^x.(1+16)=272

=> 2^x.17=272

=> 2^x=16

=> 2^x=2⁴

=> x=4

4^x + 4^{x + 2} = 272
\(\Rightarrow\)4^x + 4^x . 4² = 272
\(\Rightarrow\)4^x . ( 16 + 1 ) =  272
\(\Rightarrow\)4^x . 17 = 272
\(\Rightarrow\)4^x = 272 : 17
\(\Rightarrow\)4^x = 16
\(\Rightarrow\)4^x = 4²
\(\Rightarrow\)x = 2

a) \(\left(x+1\right)\left(x+2\right)=272\)

\(\Rightarrow x^2+3x+2=272\)

\(\Rightarrow x^2+3x-270=0\)

\(\Rightarrow x^2+18x-15x-270=0\)

\(\Rightarrow x\left(x+18\right)-15\left(x+18\right)=0\)

\(\Rightarrow\left(x+18\right)\left(x-15\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x+18=0\\x-15=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-18\\x=15\end{matrix}\right.\)

d) \(\left(x+4\right)\left(x+5\right)=552\)

\(\Rightarrow x^2+9x+20=552\)

\(\Rightarrow x^2+9x-532=0\)

\(\Rightarrow x^2+28x-19x-532=0\)

\(\Rightarrow x\left(x+28\right)-19\left(x+28\right)=0\)

\(\Rightarrow\left(x+28\right)\left(x-19\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x+28=0\\x-19=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-28\\x=19\end{matrix}\right.\)

2 bạn sai rồi!!!

2^x + 2^x + 4= 272

2^x + 2^x= 272-4

2^x + 2^x =268

2.( 2^x )=268

2^x=268:2

2^x=134

2^x=đề saI

Đề là 2^x + 2^x+4 =272  

2^x+2^x+4=272

=> 2^x.(1+2⁴)=272

=> 2^x.(1+16)=272

=> 2^x.17=272

=> 2^x=272:17

=> 2^x=16

=> 2^x=2⁴

=> x=4

2^x + 2^x +4 = 272

(2 + 2)^x  + 4 = 272

   4^x      + 4 = 272

        4^x       = 272 - 4

        4^x       = 268

2⁴+2^x+4=272

=>16+2^x.2⁴=272

=>2^x.16=272-16

=>2^x.16=256

=>2^x=256:16

=>2^x=16

=>2^x=2⁴

=>x=4