3x(2x-3)+(2x-3)(3x+1)=10 Giúp vs ạ

1 bình luận về “3x(2x-3)+(2x-3)(3x+1)=10 Giúp vs ạ”

1. → Ta có :

   3x( 2x – 3 ) + ( 2x – 3 )( 3x + 1 ) = 10

   ⇔ ( 2x – 3 )( 3x + 3x + 1 ) – 10 =0

   ⇔ ( 2x – 3 )( 6x +1 ) – 10 = 0

   ⇔ 12x² + 2x – 18x – 3 – 10 =0

   ⇔ 12x² – 16x – 13 =0

   ⇔ 12x² – 16x = 13

   ⇔ $\frac{12x² – 16x}{12}$ = $\frac{13}{12}$

   ⇔ x² – $\frac{4}{3}$x =$\frac{13}{12}$

   ⇔ x² – $\frac{4}{3}$x + $\frac{4}{9}$ = $\frac{13}{12}$ + $\frac{4}{9}$

   ⇔ ( x – $\frac{2}{3}$ )² = $\frac{55}{36}$

   ⇔ √( x – $\frac{2}{3}$ )² = √$\frac{55}{36}$

   ⇔ x – $\frac{2}{3}$ = $\frac{√55}{6}$

   ⇔ x = $\frac{√55}{6}$ + $\frac{2}{3}$

   ⇔ x = $\frac{4 + √55}{6}$

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