2x-60:15=2và (2x-15)^5=(2x-15)^3 bài tìm x

Đáp án:

   `2x -60:15=2=> x=3`

   `(2x -15)^5 =(2x-15)^3=> x\in {(15)/2;7;8}``

Giải thích các bước giải:

    `2x -60:15=2`

`<=> 2x -4=2`

`<=> 2x =2+4`

`<=> 2x =6`

`<=> x=6:2`

`<=> x=3`

Vậy `x=3`

   `(2x -15)^5 =(2x-15)^3`

`<=> (2x-15)^5 -(2x-15)^3`

`<=> (2x-15)^3 [(2x-15)^2 -1]=0`

`<=>`\(\left[ \begin{array}{l}(2x-15)^3 =0\\(2x-15)^2-1=0\end{array} \right.\) 

`<=>`\(\left[ \begin{array}{l}2x -15=0\\2x-15=±1\end{array} \right.\) 

`<=>`\(\left[ \begin{array}{l}2x =15\\2x-15=1 \\ 2x -15 =-1 \end{array} \right.\) 

`<=>`\(\left[ \begin{array}{l}2x =15\\2x=16 \\ 2x =14 \end{array} \right.\) 

`<=>`\(\left[ \begin{array}{l}x=\dfrac{15}{2}\\x=8\\ x=7\end{array} \right.\) 

Vậy `x \in {(15)/2;7;8}`

  2x - 60 : 15=2

2x-4=2

2x=2+4

2x=6

x=6:2

x=3

(2x-15)^5 = (2x-15)^3

(2x-15)^3-[(2x-15)^2-1] = 0

(2x-15)^3[(2x-15)^2-1] = 0

(2x-15)^3=0

(2x-15)^2-1 = 0

2x-15=0

2x-15 = -1;1

2x=15

2x=16;14

x=15/2

x=8

x=7

vậy x∈{15/2;8;7}