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

Toán Lớp 8: 1) Tách hoặc thêm hạng tử a) 12.x^2 + 7.x – 12 b) 5.x^2 + 6.x.y + y^2 c) 1/4.a^4 + 16.b^4 d) x^3 + x – 30

Toán Lớp 8: 1) Tách hoặc thêm hạng tử
a) 12.x^2 + 7.x – 12
b) 5.x^2 + 6.x.y + y^2
c) 1/4.a^4 + 16.b^4
d) x^3 + x – 30

Comments ( 2 )

  1. #AkaShi
    a) 12x^2+7x-12
    =12x^2+16x-9x-12
    =(12x^2+16x)-(9x+12)
    =4x(3x+4)-3(3x+4)
    =(3x+4)(4x-3)
    ………….
    b) 5x^2+6xy+y^2
    =5x^2+xy+5xy+y^2
    =(5x^2+xy)+(5xy+y^2)
    =x(5x+y)+y(5x+y)
    =(5x+y)(x+y)
    ………………..
    c) 1/4a^4+16b^4
    =1/4a^4+16b^4+4a^2b^2-4a^2b^2
    =(1/4a^4+4a^2b^2+16b^2)-4a^2b^2
    =[(1/2a^2)^2+1/2.2.4.a^2b^2+(4b^2)^2]-4a^2b^2
    =(1/2a^2+4b^2)^2-(2ab)^2
    =(1/2a^2+4b^2-2ab)(1/2a^2+4b^2+2ab)
    ………………….
    x^3-x-30
    =x^3-3x^2+3x^2+10x-9x-30
    =(x^3-3x^2)+(3x^2-9x)+(10x-30)
    =x^2(x-3)+3x(x-3)+10(x-3)
    =(x-3)(x^2+3x+10)

  2. Đáp án:
     
    Giải thích các bước giải:
     

    toan-lop-8-1-tach-hoac-them-hang-tu-a-12-2-7-12-b-5-2-6-y-y-2-c-1-4-a-4-16-b-4-d-3-30

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