Giúp mik zới: a) 25x mũ 2 – 160 =9 b) ( 2x – 1) mũ 2 – ( x – 3 ) mũ 2 =0 c) ( x + 4 ) mũ 2 – ( x – 1 ) ( x + 1 )= 16 d) ( 2x – 1 ) mũ 2 + ( x+ 3 ) mũ

0 bình luận về “Giúp mik zới: a) 25x mũ 2 – 160 =9 b) ( 2x – 1) mũ 2 – ( x – 3 ) mũ 2 =0 c) ( x + 4 ) mũ 2 – ( x – 1 ) ( x + 1 )= 16 d) ( 2x – 1 ) mũ 2 + ( x+ 3 ) mũ”

1. Đáp án + Giải thích các bước giải:

   `a)`

   `25x^2-160=9`

   `<=> 25x^2=169`

   `<=> x^2=169/25`

   `<=> x = +- 13/5`

   `b)`

   `(2x-1)^2-(x-3)^2=0`

   `<=> (2x-1-x+3)(2x-1+x-3)=0`

   `<=> (x+2)(3x-4)=0`

   `<=>`  \(\left[ \begin{array}{l}x+2=0\\3x-4=0\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=-2\\x=\dfrac{4}{3}\end{array} \right.\) 

   `c)`

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

   `<=> x^2+8x+16-(x^2-1)=16`

   `<=> x^2+8x+16-x^2+1=16`

   `<=> 8x+17=16`

   `<=> 8x=-1`

   `<=> x=-1/8`

   `d)`

   `(2x-1)^2+(x+3)^2-5(x-1)(x+1)=0`

   `<=> 4x^2-4x+1+x^2+6x+9-5(x^2-1)=0`

   `<=> 5x^2+2x+10-5x^2+5=0`

   `<=> 2x+15=0`

   `<=> 2x=-15`

   `<=> x=-15/2`

   Bình luận