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

Toán Lớp 8: 5) tính a) 5x(x^3-1/2x^2-1) ; b) (2x-1) (3x^2+5x-1/2) c) (x-2)^3 ; d)8x^3-y^3 e) 9x^2-4y^2 ; f) (x^2 -4)^2 g) (x-2y)^2 ; h) (3x+y^2)^3

Tháng Hai 7, 2023 Toán học 2 Comments 0 views

Toán Lớp 8: 5) tính
a) 5x(x^3-1/2x^2-1) ; b) (2x-1) (3x^2+5x-1/2)
c) (x-2)^3 ; d)8x^3-y^3
e) 9x^2-4y^2 ; f) (x^2 -4)^2
g) (x-2y)^2 ; h) (3x+y^2)^3
i) 343-x^3 ;k) (x-1)^2-(x+1)^2

Comments ( 2 )

  1. lanthuhoa
    lanthuhoa
    7 Tháng Hai, 2023 at 5:10 sáng
    Reply
    Lời giải và giải thích chi tiết:
     Chúc bạn học tốt nhé

    toan-lop-8-5-tinh-a-5-3-1-2-2-1-b-2-1-3-2-5-1-2-c-2-3-d-8-3-y-3-e-9-2-4y-2-f-2-4-2-g-2y-2-h-3-y

  2. haianhtu97
    haianhtu97
    7 Tháng Hai, 2023 at 5:10 sáng
    Reply
    a) 5x(x^3-1/2x^2-1)
    =5x.x^3 -5x. 1/2x^2-5x.1
    =5x^4-5/2x^3-5x
    __________________
    b) (2x-1)(3x^2+5x-1/2)
    =2x(3x^2+5x-1/2)-1.(3x^2+5x-1/2)
    =6x^3+10x^2-x-3x^2-5x+1/2
    =6x^3+7x^2-6x+1/2
    __________________
    c) (x-2)^3
    =x^3 -3x^2 .2+3.x.2^2 -2^3
    =x^3-6x^2+12x-8
    __________________
    d) 8x^3-y^3
    =(2x)^3-y^3
    =(2x-y)[(2x)^2+2x.y+y^2]
    =(2x-y)(4x^2+2xy+y^2)
    __________________
    e) 9x^2-4y^2
    =(3x)^2-(2y)^2
    =(3x+2y)(3x-2y)
    __________________
    f) (x^2-4)^2
    =(x^2)^2-2x^2 .4+4^2
    =x^4-8x^2+16
    __________________
    g) (x-2y)^2
    =x^2-2x.(2y)+(2y)^2
    =x^2-4xy+4y^2
    __________________
    h) (3x+y^2)^3
    =(3x)^3+3.(3x)^2.y^2+3x.(y^2)^2+(y^2)^3
    =27x^3+27x^2y^2+3xy^4+y^6
    __________________
    i) 343-x^3
    =7^3-x^3
    =(7-x)(7^2+7.x+x^2)
    =(7-x)(49+7x+x^2)
    __________________
    k) (x-1)^2-(x+1)^2
    =[(x-1)+(x+1)].[(x-1)-(x+1)]
    =2x.(-2)
    =-4x
    Hoặc: (x-1)^2-(x+1)^2
    =x^2-2x+1-(x^2+2x+1)
    =x^2-x^2-2x-2x+1-1
    =-4x

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

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