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

Toán Lớp 8: 3(x – 5)(x – 2)(x + 2) + 4 = 7 + 3x^3 – 15x^2

Toán Lớp 8: 3(x – 5)(x – 2)(x + 2) + 4 = 7 + 3x^3 – 15x^2

Comments ( 2 )

  1. Ta có: 3(x – 5)(x – 2)(x + 2) + 4 =7+3x³-15x²
    ⇒(3x-15).(x²+2x-2x-4)+4=7+3x³-15x²
    ⇒(3x-15).(x²-4)+4=7+3x³-15x²
    ⇒3x³-12x-15x²+60+4=7+3x³-15x²
    ⇒3x³-12x-15x²+60+4-(7+3x³-15x²)=0
    ⇒3x³-12x-15x²+60+4-7-3x³+15x²=0
    ⇒-12x+60+4-7=0
    ⇒-12x+57=0
    ⇒-12x=-57
    ⇒x=57/12
    KL:Vậy:x=57/12
    #Nocopy

  2. Giải đáp+Lời giải và giải thích chi tiết:
    3(x-5)(x-2)(x+2)+4=7+3x³-15x²
    ⇔ (3x-15)(x²-4)+4-7-3x³+15x²=0
    ⇔ 3x³-12x-15x²+60-3-3x³+15x²=0
    ⇔ 57=12x
    ⇔ x=57/12

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

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