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

Toán Lớp 8: Phân tích đa thức thành nhân tử 1) (x – 2y )^2 – x^2 2) 36x^2 – (2x – 3y)^2 3) (3a +5b )^2 – (a – b)^2 4) 4(x – 2y )^2 – (3x + y)^2

Toán Lớp 8: Phân tích đa thức thành nhân tử
1) (x – 2y )^2 – x^2
2) 36x^2 – (2x – 3y)^2
3) (3a +5b )^2 – (a – b)^2
4) 4(x – 2y )^2 – (3x + y)^2

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
    1.
    (x-2y)^2-x^2=(x-2y-x)(x-2y+x)=(-2y)(2x-2y)
    2.
    36x^2-(2x-3y)^2=(6x)^2-(2x-3y)^2
    =(6x-2x+3y)(6x+2x-3y)=(4x+3y)(8x-3y)
    3.
    (3a+5b)^2-(a-b)^2=(3a+5b-a+b)(3a+5b+a-b)
    =(2a+6b)(4a+4b)
    =2(a+3b)*4(a+b)
    =8(a+3b)(a+b)
    4.
    4(x-y)^2-(3x+y)^2=[2(x-y)]^2-(3x+y)^2
    =(2x-2y)^2-(3x+y)^2
    =(2x-2y-3x-y)(2x-2y+3x+y)
    =(-x-3y)(5x-y).
     

  2. 1) (x-2y)^2 – x^2
    = x^2 -4xy + 4y^2 – x^2
    = 4y^2 – 4xy
    2) 36x^2 – (2x – 3y)^2
    = (6x)^2 – (2x – 3y )^2
    = (6x+ 2x – 3y)(6x- 2x + 3y)
    3) (3a +5b )^2 – (a – b)^2
    = (3a+5b+a-b)( 3a+5b-a+b)
    = (4a+4b)(2a+6b)
    = 4(a+b)(a+3b)
    4) 4(x – 2y )^2 – (3x + y)^2
    = (2x- 8y)^2 – (3x+y)^2
    = (2x-8y+3x+y)(2x-8y-3x-y)
    = -(5x-7y)(x+9y)

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

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