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

Toán Lớp 8: Rut gon bieu thuc a, M=(2a+b)^2-(b-2a)^2 b, N=(3a+2)^2+2*(2+3a)*(1-2b)+(2b-1)^2

Toán Lớp 8: Rut gon bieu thuc
a, M=(2a+b)^2-(b-2a)^2
b, N=(3a+2)^2+2*(2+3a)*(1-2b)+(2b-1)^2

Comments ( 2 )

  1. a)M=(2a+b)^2-(b-2a)^2
    =4a^2+4ab+b^2-b^2+4ab-4a^2
    =8ab
    N=(3a+2)^2+2(2+3a)(1-2b)+(2b-1)^2
     =(3a+2)^1-2(2+3a)(2b-1)+(2b-1)^2
    =(3a+2-2b+1)^2
    =(3a-2b+3)^2
    =9a^2-4b^2+9-12ab-12b+18a

  2. a,M=(2a+b)^2-(b-2a)^2
    =(2a+b+b-2a)[2a+b-(b-2a)]
    =2b(2a+b-b+2a)
    =2b.4a
    =8ab
    b,N=(3a+2)^2+2(2+3a)(1-2b)+(2b-1)^2
    =(3a+2)^2+2(3a+2)(1-2b)+(1-2b)^2
    =(3a+2+1-2b)^2
    =(3a-2b+3)^2

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

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