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

Toán Lớp 8: Tìm x, biết: 4x^2 – 25 + (2x + 7) (5 – 2x) = 0

Tháng Tám 2, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Tìm x, biết:
4x^2 – 25 + (2x + 7) (5 – 2x) = 0

Comments ( 2 )

  1. hauthanhyen98
    hauthanhyen98
    2 Tháng Tám, 2022 at 11:15 chiều
    Reply
    4x^2-25+(2x+7)(5-2x)=0
    <=> -(25-4x^2)+(2x+7)(5-2x)=0
    <=> -(5+2x)(5-2x)+(2x+7)(5-2x)=0
    <=>(5-2x)[-(5+2x)+(2x+7)]=0
    <=>(5-2x)(-5-2x+2x+7)=0
    <=>2(5-2x)=0
    <=>5-2x=0
    <=>2x=5
    <=>x=5/2
    Vậy x=5/2

  2. dongoclandiem
    dongoclandiem
    2 Tháng Tám, 2022 at 11:15 chiều
    Reply
    4x^2 – 25 + (2x+7)(5-2x) = 0
    4x^2 – 25 + 10x – 4x^2 + 25 – 14x=0
    (4x^2 – 4x^2 ) + (10x -14x) + (-25+25)=0
    -4x=0
    => x =0
     

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

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