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

Toán Lớp 8: a)(3x-1)(2x+3)-(x-5)(6x-1)-38x b)(x-2y)(x^2+2xy+4y^2)-x^3+5+8y^3) c)(5x-2)(x+1)-(x-3)(5x+1)-17(x-2)

Tháng Sáu 13, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: a)(3x-1)(2x+3)-(x-5)(6x-1)-38x
b)(x-2y)(x^2+2xy+4y^2)-x^3+5+8y^3)
c)(5x-2)(x+1)-(x-3)(5x+1)-17(x-2)

Comments ( 2 )

  1. lanngocha
    lanngocha
    13 Tháng Sáu, 2022 at 1:25 sáng
    Reply
    a) (3x-1)(2x+3)-(x-5)(6x-1)-38x
    =6x^2+9x-2x-3-6x^2+x+30x-5-38x
    =-3-5
    =-8
     b) (x-2y)(x^2+2xy+4y^2)-x^3+5+8y^3
    =x^3-8y^3-x^3+5+8y^3
    =5
     c) (5x-2)(x+1)-(x-3)(5x+1)-17(x-2)
    =5x^2+5x-2x-2-5x^2-x+15x+3-17x+34
    =2x+8

  2. daithanh
    daithanh
    13 Tháng Sáu, 2022 at 1:24 sáng
    Reply
    Giải đáp + Lời giải và giải thích chi tiết:
     a) (3x-1)(2x+3) – (x-5)(6x-1) -38x
    = 6x^2 – 2x + 9x – 3 – (6x^2 – 30x – x + 5 ) – 38x
    = 6x^2 – 31x – 3 – 6x^2 + 31x – 5
    = -8
    b) (x-2y)(x^2 + 2xy + 4y^2 ) – x^3 + 5 + 8y^3
    = (x-2y)[x^2 + x.2y + (2y)^2] – x^3 + 5 + 8y^3
    = x^3 – (2y)^3 – x^3 + 5 + 8y^3 = 5
    c) (5x-2)(x+1) – (x-3)(5x-1) – 17(x-2)
    = 5x^2 – 2x + 5x – 3 – ( 5x^2 – 15x – x + 3 ) – 17x + 34
    = 5x^2 -14x + 31 – 5x^2 + 16x – 3
    = 2x + 28

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

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