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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: C=2(3x+5)^2-2x(3x+1)(3x-1) rút gọn ạ cảm ơn ai lm đc

Toán Lớp 8: C=2(3x+5)^2-2x(3x+1)(3x-1) rút gọn ạ cảm ơn ai lm đc

Comments ( 1 )

  1. C = 2(3x + 5)² – 2x(3x + 1)(3x – 1)
       = 2.[(3x)² + 2.3x.5 + (5)²] – 2x.[(3x)² – (1)²]
       = 2(9x² + 30x + 25)- 2x(9x² – 1)
       = (2.9x² + 30x.2 + 25.2) – (9x².2x – 1.2x)
       = 18x² + 60x + 50 – 18x³ + 2x 
       = -18x³ + 18x² + 62x + 50
     

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222-9+11+12:2*14+14 = ? ( )

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