Đáp án:

`a)`\(\left[ \begin{array}{l}x=3/5\\x=-3/5\end{array} \right.\) 

`b)`\(\left[ \begin{array}{l}x=5\\x=1\end{array} \right.\) 

`c)`\(\left[ \begin{array}{l}x=-4\\x=6\end{array} \right.\) 

`d)x=-1/8`

`e)x=-255/2`

Giải thích các bước giải:

`a) 25x ² - 9=0`

`⇒(5x)²-3²=0`

`⇒(5x-3)(5x+3)=0`

`⇒`\(\left[ \begin{array}{l}5x-3=0\\5x+3=0\end{array} \right.\) 

`⇒`\(\left[ \begin{array}{l}5x=3\\5x=-3\end{array} \right.\) 

`⇒`\(\left[ \begin{array}{l}x=3/5\\x=-3/5\end{array} \right.\) 

`b) (x-3) ² - 4=0`

`⇒(x-3)²-2²=0`

`⇒(x-3-2)(x-3+2)=0`

`⇒(x-5)(x-1)=0`

`⇒`\(\left[ \begin{array}{l}x=5\\x=1\end{array} \right.\) 

`c)x²-2x=24`

`⇒ x²-2x-24=0`

`⇒(x+4)(x-6)=0`

`⇒`\(\left[ \begin{array}{l}x=-4\\x=6\end{array} \right.\) 

`d)(x+4)²-(x+1)(x-1)=16`

`⇒x²+8x+16-x²+1-16=0`

`⇒8x=-1`

`⇒x=-1/8`

`e)(2x-1)²+(x+3)²-5(x+7)(x-7)=0`

`⇒4x²-4x+1+x²+6x+9-5x²+245=0`

`⇒2x+255=0`

`⇒x=-255/2`

Bạn tham khảo ạ !

Đáp án:

 a) 25x^2 - 9 = 0 

= (5x)^2 - 3^2 = 0

= ( 5x - 3 ) ( 5x + 3 ) = 0

[ 5x - 3 = 0 => 5x = 3 => x = 3/5

[ 5x + 3 = 0 => 5x = -3 => x = -3/5

b) (x-3)^2 - 4 = 0 

(x-3)^2 - 2^2 = 0

( x - 3 -2 ) ( x - 3 + 2 ) = 0

[ x - 3 - 2 = 0 => x = 5

[ x - 3 + 2 = 0 => x = 1

c) x^2 - 2x = 24 

= x^2 - 2x -24 = 0 

= x^2 - 6x + 4x -24 = 0 

= ( x - 6 ) ( x + 4 ) = 0

[ x - 6 = 0 => x = 6

[ x + 4 = 0 => x = -4

d) (x+4)^2 - ( x+ 1) ( x -1) = 16

x^2 + 8x +16 - x^2  + 1 = 16

8x + 17 = 16

8x = 16 - 17

8x = - 1

x = -1/8

e) 3(x - 1)^2 - 3x ( x - 5 ) = 1

3. ( x^2 - 2x + 1 ) - 3x^2 +15x = 1

3x^2 - 6x + 3 - 3x^2 + 15x = 1

9x + 3 = 1

9x = 1-3

9x = -2

x = -2/9

Xin ctlhn ạ :333

Giải thích các bước giải: