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

Toán Lớp 8: rút gọn a. (2x+3)(2x-3)-(5x-1)^2 b. 2x(3x+1)+(x+3)(2x-3)

Tháng Bảy 3, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: rút gọn
a. (2x+3)(2x-3)-(5x-1)^2
b. 2x(3x+1)+(x+3)(2x-3)

Comments ( 2 )

  1. huongtructram
    huongtructram
    3 Tháng Bảy, 2022 at 2:00 chiều
    Reply
    a) (2x+3)(2x-3)-(5x-1)^2
    =4x^2-9-25x^2+10x-1
    =-21x^2+10x-10
    b) 2x(3x+1)+(x+3)(2x-3)
    =6x^2+2x+2x^2-3x+6x-9
    =8x^2+5x-9
     

  2. hongocha12
    hongocha12
    3 Tháng Bảy, 2022 at 2:00 chiều
    Reply
    a, ( 2x+3)(2x-3) – (5x-1)^2
    = (2x)^2 – 3^2 – [ (5x)^2 – 2.5x.1 + 1]
    = 4x^2 – 9 – ( 25x^2 – 10x + 1)
    = 4x^2 – 9 – 25x^2 + 10x -1
    = -21x^2 + 10x -10
    b, 2x(3x+1) + (x+3)(2x-3)
    = 6x^2 + 2x + 2x^2 – 3x + 6x – 9
    = 8x^2 + 5x -9
    \color{green}{\text{@BerryLinh}}
     

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

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