n.(2x-5)²=9

(2x-5)²=3²

* 2x-5=3       * 2x-5=-3

2x=3+5           2x=-3+5

2x=8               2x=2

  x=8:2              x=2:2

  x=4                 x=1

vậy x=4 hoặc x=1

o.(1-3x )³=-8 

(1-3x)³=(-2)³

1-3x=-2

3x=1-(-2)

3x=3

  x=3:3

  x=1

vậy x=1

Hình như đề sai nếu viết thế này:x + (x+1) + (x+2) + (x+3) + .... + 13 + 14 = 14

Thì biết chỗ nào ko có x chỗ nào có x

Chúc bn học tốt

a)(x - 45) . 27 = 0 

x-45=0:27

x-45=0

x=0+45

x=45.

b)23 . (42 - x) = 23

42-x=23:23

42-x=1

x=42-1

x=41

Câu 1:

a)(x-45)*27=0.

=>x-45=0:27.

=>x-45=0.

=>x=0+45.

=>x=45.

Vậy......

b)23*(42-x)=23.

=>42-x=23:23.

=>42-x=1.

=>x=42-1.

=>x=41.

Vậy....

Câu 2:Có vấn đề về đề bài.

a)\(\left|x-8\right|=19\)

TH1:x-8=-19

       x=-11

TH2:x-8=19

       x=27

b)\(\left|x+14\right|=492\)

TH1:x+14=492

      x=478

TH2:x+14=-492

      x=-506

\(\left|x-8\right|=19\)

\(\Rightarrow\orbr{\begin{cases}x-8=19\\x-8=-19\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=27\\x=-11\end{cases}}\)

\(\left|x+14\right|=492\)

\(\Rightarrow\orbr{\begin{cases}x+14=492\\x+14=-492\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=478\\x=-506\end{cases}}\)

a) |2x + 1| - 19 = -7

=> \(\left|2x+1\right|=-7+19=12\)

=> \(\left[{}\begin{matrix}2x+1=12\\2x+1=-12\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}2x=12-1=11\\2x=-12-1=-13\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}x=\frac{11}{2}\\x=-\frac{13}{2}\end{matrix}\right.\)

Vậy:............

b) -28 – 7. |- 3x + 15| = -70

=> \(\text{7. |- 3x + 15| = -28 - (-70) = -28 + 70 = 42}\)

=> \(\left|-3x+15\right|=42:7=6\)

=> \(\left[{}\begin{matrix}-3x+15=6\\-3x+15=-6\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}-3x=6-15=-9\\-3x=-6-15=-6+\left(-15\right)=-21\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}x=-9:\left(-3\right)=3\\x=x=-21:\left(-3\right)=7\end{matrix}\right.\)

Vậy:.....................

c) |18 – 2. |-x + 5|| = 12

=> \(\left[{}\begin{matrix}18-2.\left|-x+5\right|=12\\18-2.\left|-x+5\right|=-12\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}2.\left|-x+5\right|=18-12=6\\2.\left|-x+5\right|=18-\left(-12\right)=18+12=30\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}\left|-x+5\right|=6:2=3\\\left|-x+5\right|=30:2=15\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}\left[{}\begin{matrix}-x+5=3\\-x+5=-3\end{matrix}\right.\\\left[{}\begin{matrix}-x+5=15\\-x+5=-15\end{matrix}\right.\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}\left[{}\begin{matrix}-x=3-5=-2\\-x=-3-5=-8\end{matrix}\right.\\\left[{}\begin{matrix}-x=15-5=10\\-x=-15-5=-20\end{matrix}\right.\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}\left[{}\begin{matrix}x=2\\x=8\end{matrix}\right.\\\left[{}\begin{matrix}x=-10\\x=20\end{matrix}\right.\end{matrix}\right.\)

thank bn ✰❤❤✔