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

Toán Lớp 8: Bài 2 a) (x^2 + 2xy + y^2) : (x + y); b) (125x^3 + 1) : (5x + 1); c) (x^2 – 2xy + y^2) : (y – x). d) (25x^5 – 5x^4 + 10x^2) : 5x^2; e)

Toán Lớp 8: Bài 2
a) (x^2 + 2xy + y^2) : (x + y);
b) (125x^3 + 1) : (5x + 1);
c) (x^2 – 2xy + y^2) : (y – x).
d) (25x^5 – 5x^4 + 10x^2) : 5x^2;
e) (15x^3y^2 – 6x^2y – 3x^2y^2) : 6x^2y.
Bài 3
Tính nhanh:
a) (4x^2 – 9y^2) : (2x – 3y); b) (27x^3 – 1) : (3x – 1);
c) (8x^3 + 1) : (4x^2 – 2x + 1); d) (x^2 – 3x + xy -3y) : (x + y)

Comments ( 1 )

  1. ~ gửi bạn ~
    Giải đáp:
    …….. 
    Lời giải và giải thích chi tiết:
    2)
    a) (x^2 + 2xy + y^2) : (x + y) = (x + y)^2 : (x + y) = x + y.
    b) (125x^3 + 1) : (5x + 1) = [(5x)^3 + 1] : (5x + 1)= (5x)^2 – 5x + 1 = 25x^2 – 5x + 1.
    c) (x^2 – 2xy + y^2) : (y – x) = (x – y)^2 : [-(x – y)] = – (x – y) = y – x
    d) (25x^5 – 5x^4 + 10x^2) : 5x^2 = (25x^5 : 5x^2 ) – (5x^4 : 5x^2 ) + (10x^2 : 5x^2) = 5x^3 – x^2 + 2
    e) (15x^3y^2 – 6x^2y – 3x^2y^2) : 6x^2y = (15x^3y^2 : 6x^2y) + (– 6x^2y : 6x^2y) + (– 3x^2y^2 : 6x^2y) = 15/6xy – 1 – 3/6y = 5/2xy – 1/2y – 1.
    ——————————————–
    3)
    a) (4x^2 – 9y^2) : (2x – 3y) = [(2x)^2 – (3y)^2] : (2x – 3y) = (2x –3y)(2x +3y) : (2x –3y) = 2x + 3y
    b) (27x^3 – 1) : (3x – 1) = [(3x)^3 – 1] : (3x – 1) = (3x – 1) [(3x)^2 + 3x + 1] : (3x – 1) = 9x^2+ 3x + 1
    c) (8x^3 + 1) : (4x^2 – 2x + 1)
    = [(2x)^3 + 1] : (4x^2 – 2x + 1)
    = (2x + 1)[(2x)^2 – 2x + 1] : (4x^2 – 2x + 1)
    = (2x + 1)(4x^2 – 2x + 1) : (4x^2 – 2x + 1)
    = 2x + 1
    d) (x^2 – 3x + xy -3y) : (x + y)
    = [(x^2 + xy) – (3x + 3y)] : (x + y)
    = [x(x + y) – 3(x + y)] : (x + y)
    = (x + y)(x – 3) : (x + y)
    = x – 3

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

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