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Toán Lớp 8: A, (1/3x-2) – (1/3x+2) – (3x-6/4-9x^2) B, (7/x) – (x/x+6) +(36/x^2+6x)

Home/ Toán Lớp 8: A, (1/3x-2) – (1/3x+2) – (3x-6/4-9x^2) B, (7/x) – (x/x+6) +(36/x^2+6x)

Toán Lớp 8: A, (1/3x-2) – (1/3x+2) – (3x-6/4-9x^2) B, (7/x) – (x/x+6) +(36/x^2+6x)

Chi Mai Tháng Mười 16, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: A, (1/3x-2) – (1/3x+2) – (3x-6/4-9x^2)
B, (7/x) – (x/x+6) +(36/x^2+6x)

Comments ( 1 )

hatuanlan
16 Tháng Mười, 2022 at 9:57 chiều

Reply

$ A = \dfrac{1}{3x-2} – \dfrac{1}{3x+2} – \dfrac{3x-6}{4-9x^2} $

$ = \dfrac{1}{3x-2} – \dfrac{1}{3x+2} + \dfrac{3x-6}{( 3x + 2 ) ( 3x – 2 )} $

$ = \dfrac{3x+2-3x+2+3x-6}{(3x+2)(3x-2)}$

$ = \dfrac{-3x -2}{( 3x + 2 ) ( 3x – 2 )}$

$ = \dfrac{-(3x+2)}{( 3x + 2 ) ( 3x – 2 )}$

$ = \dfrac{-1}{3x-2}$

————————————-

$ B = \dfrac{7}{x} – \dfrac{x}{x+6} + \dfrac{36}{x^2+6x} $

$ = \dfrac{7 ( x + 6 ) – x . x + 36 }{ x ( x + 6 ) } $

$ = \dfrac{7x+42-x^2 + 36 }{ x ( x + 6 )} $

$ = \dfrac{- ( x + 6 ) ( x – 13 ) }{ x ( x + 6 )} $

$ = \dfrac{13-x}{x} $

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