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

Toán Lớp 8: kết quả rút gọn biểu thức (2x – 5)^2 – 4x (x – 5) + 10 A.25 B.28 C.10 D.35

Toán Lớp 8: kết quả rút gọn biểu thức (2x – 5)^2 – 4x (x – 5) + 10
A.25 B.28 C.10 D.35

Comments ( 2 )

  1. (2x-5)^2 – 4x(x-5)+10
    = 4x^2 – 20x + 25 – 4x^2 + 20x + 10
    = (4x^2 – 4x^2) + (-20x + 20x) + 25 + 10
    = 35
    ⇒ D. 35

  2. (2x-5)^2-4x(x-5)+10
    =4x^2-20x+25-4x^2+20x+10
    =(4x^2-4x^2)+(20x-20x)+(25+10)
    =35
    ->D
    * (a-b)^2=a^2-2ab+b^2

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

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