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

Toán Lớp 8: Rút gọn biểun thức x^2 (x – 4)(x + 4) – (x^2 + 1)(x^2 – 1)

Toán Lớp 8: Rút gọn biểun thức x^2 (x – 4)(x + 4) – (x^2 + 1)(x^2 – 1)

Comments ( 2 )

  1. #tnvt
    x^2(x-4)(x+4)-(x^2+1)(x^2-1)
    =x^2(x^2-4^2)-[(x^2)^2-1^2]
    =x^2(x^2-16)-(x^4-1)
    =x^4-16x^2-x^4+1
    =-16x^2+1
    $\\$
    Áp dụng HĐT: a^2-b^2=(a-b)(a+b)

  2. x^2 (x – 4)(x + 4) – (x^2 + 1)(x^2 – 1)
    = x^2[x^2−42]−[(x^2)^2−1^2]
    =x^4−16x−x^4+1
    =(x^4-x^4)−16x^2+1
    =−16x^2+1

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

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